Physics – Flashcards
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Giga
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10^9 (G)
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Mega
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10^6 (M)
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Kilo
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10^3 (k)
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deci
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10^-1 (d)
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Centi
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10^-2 (c)
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milli
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10^-3 (m)
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micro
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10^-6 (u)
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nano
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10^-9 (n)
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how do you add vectors?
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add them tip to tail
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When you multiply a vector by a positive # what happens?
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the vector will keep pointing in the same direction
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If you multiply a vector by a negative # what happens?
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the vector will point in the opposite direction
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What is the x component of a vector?
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Ax= +|A|cosθ
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What is the y component of a vector?
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Ay= +|A|sinθ
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What is the Cx component of a new vector ?
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Cx= Ax + Bx
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What is the Cy component of a new vector?
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Cy=Ay +By
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What is |C| of a new vector?
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|C|=√Cx²+Cy²
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A vector by itself is neither ___ or _____
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negative or positive. it has a size and direction
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displacement (∆X=Xf-Xi)
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a vector that points from the initial position to the final position
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velocity is
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the rate of change (in time) of your displacement. in 1 dimension it is the slope of the displacement vs time plot.
Vave= ∆x/∆t
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What is speed?
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just the magnitude of the velocity
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An object is accelerating if...
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its velocity is changing in any way at all
-speeding up
-slowing down
-same speed but changing direction
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What is acceleration
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rate in change (in time) of your velocity (slope of velocity vs time plot). the sign of acceleration on tells direction!!!
a=∆V/∆T
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area of velocity vs time gives what?
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change in position (∆X)
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area under acceleration vs time gives what?
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change in velocity (∆a)
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a net force means that there is
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a change in velocity so it could mean a change in speed, a change in direction, or a combination of these
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a compressed spring exerts a
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pushing force on an object
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a stretched spring exerts a
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pulling force on an object
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the tension force points
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along the string away from the object
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normal force
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it is perpendicular to the object away from the surface
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friction force
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other force from surface, it points parallel to the surface, it opposes the direction of sliding
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kinetic friction occurs when there is
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sliding
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static friction occurs when there is
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no sliding
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the net force on an object points in the direction of the ------ of the object
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acceleration
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f grav =
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mg
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g is
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the acceleration due to the force of gravity or free fall acceleration on the earth
-always positive
-not a vector
-not called gravity
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if an object is in free fall, what is the acceleration?
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it is g downwards
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Newton's 3rd Law
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every force occurs as one member of an action/reaction pair of forces.
-the two members of an action/reaction pair act on two different objects
-the two members of an action/reaction pair point in opposite directions and are equal in magnitude
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kinetic friction 'Fk'=
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Uk|Fn|
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Static friction 'Fs'≤
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Us|Fn|
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how do you calculate a frictional coefficient?
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usually use newtons 2nd law to solve for them
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What is the equation for tension force?
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there is none! you need to use 2nd law
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What do pulleys do?
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they redirect the tension force acting on a rope/string, etc, this allows us to amplify an applied force
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drag force depends on
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velocity! drag fore always points opposite the velocity
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when an object is falling from rest, the acceleration becomes zero, and the speed doesn't change. what is this called
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terminal velocity or terminal speed
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what is statics?
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a special case of 2nd law where a = 0
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What is a vector?
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a quantity having both size and direction
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For one-dimensional motion, by examining the slope of an object's position vs. time plot we can find
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the velocity
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Which of the following quantities is NOT a vector?
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speed
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For one-dimensional motion, by examining the slope of an object's position vs. time plot we can find
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the velocity
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An object is moving with a certain velocity. In order for the object to KEEP moving with the same velocity there must be
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no net (total) force acting on the object
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The net force on an object points
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1. in the same direction as the object's change in velocity.
2. in the same direction as the acceleration of the object.
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An action/reaction pair of forces
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1. point in the opposite direction.
2. act on two different objects
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When an object is moving under the influence of gravity only, and no other forces, the motion is called .
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free fall
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"g'' is...
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always positive
called the "acceleration due to gravity"
different on every planet.
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The magnitude of the kinetic friction force
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is always equal to μk|FN|
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The magnitude of the static friction force...
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is equal to or less than μs|FN|
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The coefficient of static friction is
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usually larger than the coefficient of kinetic friction.
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Which of the following is a way to increase the drag force acting on an object?
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Increase the area of the object
Move the object faster
Make the stuff the object is moving through more dense.
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"Static equilibrium" means
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the net force acting on an object is zero
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The forces acting on an object undergoing projectile motion are
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The force of gravity (from the Earth/planet), and possibly the drag force
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For an object undergoing the simplest type of projectile motion (ignoring the drag force), the acceleration of the object is
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g vertically downward and 0 horizontally
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Check the boxes beside the statements that are TRUE, regarding force and motion.
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If an object at rest remains at rest, the net force acting on it must be zero.
If there is a net force acting on an object, the object's velocity will change.
If an object has a constant velocity, the net force acting on it must be zero
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The net force on a moving object is suddenly reduced to zero. What happens as a result of this?
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The object continues moving with a constant velocity.
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The Normal Force acting on an object
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points perpendicular to the to the surface the object rests on
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A "reference frame" is
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an observer's choice of axes (origin and direction) for making measurements.
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An "Inertial Reference Frame" is
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a set of corrdinates that moves with a constant velocity
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Newton's 2nd Law is NOT valid in.
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accelerated reference frames
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For uniform circular motion (moving in a circle with a constant speed), the net force
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points toward the center of the circle
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"Apparent Weight" is
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the magnitude of the contact force that supports the object
how heavy you feel.
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When we say that an object is "weightless", we mean that
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the object has no sensation of weight (apparent weight)
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If a system is isolated, then the total energy of the system
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is constant in time.
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Can Kinetic Energy ever be negative?
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No, if an object is moving, that takes some amount of energy, which must be positive.
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Gravitational Potential Energy for a system which includes the Earth and a smaller object depends on
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the strength of the Earth's gravity (the size of "g")
the height of the object above the Earth
the mass of the object
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Potential Energy..
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is energy that a system has by virtue of its position.
is the property of multiple objects interacting through a force.
arises from forces where the work done is independent of the path taken.
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In an isolated system without friction,
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mechanical energy is conserved.
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Power is
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the rate at which work is done.
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Impulse is
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the area under the curve of a force vs time plot.
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A particular impulse is given to an object by using a small force for a long amount of time. The same impulse could have been given to the object by using
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a large force for a small amount of time.
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When is the total momentum of a system conserved?
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When the system is isolated.
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An elastic collision is a collision where
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the system's momentum is conserved, and the system's kinetic energy is conserved.
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An inelastic collision is a collision where..
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the system's momentum is conserved, but the kinetic energy of the system is not conserved.
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A completely inelastic collision is a collision where
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both objects in the collision move with the same velocity after the collision
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The location of the center of mass of an object (or collection of objects) is
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at the "balance point" of the object (or collection of objects).
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The motion of the center of mass of an object (or collection of objects) is only affected by...
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forces external to the object (or collection of objects).
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Which things does the torque that a force exerts on an object depend on?
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The distance from the axis to the point at which the force is applied.
The angle at which the force is applied.
The magnitude of the force.
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Moment of Inertia is.
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the rotational equivalent of mass.
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What condition or conditions must be met for a rigid body to be in rotational equilibrium?
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Both the net force and net torque on the object must be zero.
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For an extended object (an object that is not just a point) that is moving, the total kinetic energy is given by....
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the translational KE (of the center-of-mass) plus the rotational KE (about the center-of-mass).
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The angular momentum of an object is conserved when....
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the net external torque on the object is zero.
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The difference between absolute pressure and atmospheric pressure is called....
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gauge pressue.
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Typically, as you go deeper in a fluid, the pressure in the fluid...
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increases
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The buoyant forcce on an object is equal to....
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the weight of the fluid displaced by the object.
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Heat is
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energy that enters or leaves a system because of a temperature difference.
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According to the zeroth law of thermodynamics, if two objects are in equilibrium with each other, then they have....
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the same temperature.
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In our textbook, the first law of thermodynamics is given as ∆U = Q − W. Written this way, the "W" stands for...
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work done BY the system ON the surroundings/environment.
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In our textbook, the first law of thermodynamics is given as ∆U = Q − W. Written this way, the "Q" stands for....
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heat GIVEN TO the system.
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Which of the following statements correctly describes heat flow?
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Heat never spontaneously flows from cold to hot.
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A heat engine operates by....
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moving heat out of a hot reservoir to do work.
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In an irreversible process, the total change in entropy is...
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greater than zero
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The change in entropy of a single object in a thermodynamic process....
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can be positive, negative, or zero.
