Real ap physics flash cards – Flashcards
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Distance vs displacement
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Distance- how far you've actually traveled Displacement- how far from your starting position you've traveled
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Velocity of an object in parabolic motion
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Stops at the top of the parabola
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What is the acceleration of an object whose position-time graph is a straight line?
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Zero
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An object moves with a constant, negative acceleration. What is the shape of the position-time graph?
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Parabolic, the parabola opens downward
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In what case does a car have a negative velocity and a positive acceleration?
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-x direction decreasing in speed
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At time t=0 an object is traveling to the right along the +x axis at a speed of 10m/s with an acceleration of -2.0m/s. What will happen to the objects speed and direction over time?
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The object will slow down, momentarily stopping, then pick up speed moving to the left
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A ball is thrown straight up. What are the velocity and acceleration of the ball at the highest point in its path?
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Velocity = 0 m/s Acceleration = 9.8 m/s down
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If a ball that is thrown downward has an acceleration of magnitude a at the instant of its release, what is the relationship between a and g?
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a = g
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A ball is thrown down and a ball is dropped, which has a greater acceleration at the instant of release?
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Neither- the acceleration of both balls are the same
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A ball is thrown down and a ball is dropped, which has a greater speed at the instant of release?
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Neither- the speeds are the same
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A ball is thrown down and a ball is dropped, which has a greater average speed during the 1-s interval after release?
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The ball thrown downward
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A ball is thrown down and a ball is dropped, which hits the ground with greater speed?
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Neither- both balls hit the ground with the same speed
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You drop a rock off a bridge. When the Rock has fallen 4m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities?
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Both increase at the same rate
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A baseball player hots a ball. After the ball has left the bat and while it is traveling upward, what is the direction of acceleration?
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Straight down
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A cannon is pointed straight up and fired. How would the acceleration of the ball be described?
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A constant downward acceleration
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How can you decrease the speed of a package dropped from a flying plane?
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Decrease plane's speed and height
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A bullet fired from a rifle begins to fall
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As soon as it leaves the barrel
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You are riding a train moving at 90km/h. If you throw a ball straight up, where will the ball land?
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In your hand
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A baseball if hit high and far. At the highest point, what can be said about its velocity?
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The magnitude of the velocity of the slowest
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The crew of a cargo plane wishes to drop a crate of supplies on a target below. To hit the target when should the crew drop the crate?
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Before the place is directly over the target
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Suppose an object is accelerated by a force of 100 N. Suddenly a second force of 100 N in the opposite direction is exerted on the object, so that the forces cancel. What happened to the objects velocity?
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Continues at the same velocity it had before the second force was applied
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A bucket is lowered vertically by a rope in which there is tension. Is its direction directed up or down?
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Up
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A woman if standing on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only .82 of her regular weight. What direction is the acceleration?
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Downward
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Finding coefficient of friction
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Force of friction = Fnormal • coefficient of friction
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What causes the boat to move forward?
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The force the water exerts on the paddle
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Every force has one and only one 3rd law pair force (true/false)
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True
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The two forces of a 3rd law pair always act on different objects (true/false)
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True
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An astronaut is taking a space walk near the shuttle when her safety tether breaks. What should the astronaut do to get back to the shuttle?
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Take a toll from her tool belt and throw it away from the shuttle
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If a car is moving to the left with constant velocity, one can conclude about the net force that
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The net force is zero
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You are pushing a heavy box across a rough floor: when you are initially pushing the box and it is accelerating
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The force you exert on the box is equal to the force pushing back on you
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As the backpacker raises their bear sling by pulling down on a rope- The force needed
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Increase but the rope always sags where the pack hangs
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When a skier skis down a hill the normal force exerted on the skier by the hill is
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Less than the weight of the skier
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While driving fast around a sharp right turn, you find yourself pressing against a car door, what is happening?
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The sort is exerting a rightward force on yo. Centripetal force is not pushing you into the door
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Acceleration and net force always point towards what direction when moving in a circular uniform motion?
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Towards the center
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A child whirls a ball in a vertical circle. When would tension in the cord connected to the ball be the greatest?
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At the bottom of the circle
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Which pulls harder gravitationally, the earth on the moon or the the moon on the earth? Which is accelerating more?
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Both the same force. Moon accelerating faster
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Two satellites orbit the earth in a circular orbits of the same radius. One satellite is twice as massive as the other. Which statement is true about the speeds of the satellites?
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The two satellites have the same speed
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The ball is thrown straight up. At what point does the bull have the most energy?
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Everywhere the energy of the ball is the same at all of these points
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A ball is thrown straight up. What is not true regarding the energy of the ball?
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The potential energy decreases when the ball is going up
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After ball leaves circular track
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Will follow a straight line oath from direction it left the track from
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Two identical satellites orbit the earth. One satellite orbits with the speed V at a distance or from the center of the earth. The second set of light travels at the speed that is less than V. At what distance from the center of the earth does a second satellites orbit?
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At a distance greater than r
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As projectile goes upward, what energy changes that place?
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Kinetic energy decreases, potential energy increase
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At the top of the projectile, what can be said about the projectiles kinematic and potential enegy
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Kinetic energy is minimums and potential energy is at it's maximum
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Impulse relationship with force
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Impulse= force • time
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A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a wall. Which one has a greater change in momentum?
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The rubber ball because it bounces back and has a change in direction
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A giant explodes. During the explosion, is the magnitude of the force of piece A on piece B greater than, less than, or equal to the magnitude of the force of piece B on piece A
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Equal
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The space shuttle, I'm circular orbit around the earth, collides with a small asteroid which ends up in the shuttles storage bay. What is conserved in this collision, momentum or kinetic energy?
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Only momentum
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A railroad tank car contains milk and tools at a constant speed along a level track. The milk begins to leak out the bottom- what happens to the speed of the car?
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Maintains constant speed
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Two ladybugs sit on a rotating discs, on with a radius of r and the other with a radius of 2r. What isn the angular speed of ladybug 1?
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Same as ladybug 2
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Centripetal acceleration
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V^2/r
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Two children are balanced on opposite side of a seesaw. If one child leans inward towards the pivot point, her side will
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Rise
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To sphere have the same radius in equal mess. One sphere is solid and the others hollow and made of a denser material. Which one has a bigger moment of inertia?
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The hollow one
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Bonnie sits on the outer rim of a merry go round and Jill sits midway between the center and the rim. The merry go round makes one complete revolution every 2 seconds. Jill's linear velocity is
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Half of Bonnie's
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An object at rest begins to rotate with a constant angular acceleration. If the object rotates through angle ø in time t, through what angle did it rotate in the time 1/2t?
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1/4ø
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A car speedometer that is suppose to read the linear speed of a car uses a device that actually measures the angular speed of the tires. If a large diameter tires are mounted on the car instead, how will this affect the speedometer reading?
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The speedometer will read low because angular velocity of small and large diameter tires are the same but a larger diameter means a larger linear distance traveled
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When a cyclist encounters a steep hill she changes gears to .7 to maintain speed. What change is caused by this new gear ratio?
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The torque exerted on the rear gear wheel increases
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Suppose you are standing on the center of a merry go round at rest. You are holding a spinning bicycle wheel over your head so that its rotation axis is pointing upward. The wheel is rotating counter clockwise. You grab the edge of the wheel with your hand, stopping it from spinning. What happens to the merry go round?
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It begins to rotate counterclockwise
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A small mass in a string is rotating without friction in a circle. The string is shortened by pulling it through the axis of rotation without any external force. What happens to the tangential velocity of the object?
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It increases
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Starting at rest, a solid sphere rolls without skipping down an incline plane. At the bottom of the incline, what does the angular velocity of the sphere depend on?
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Height of incline, radius of sphere
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A constant net torque is applied to a rotating object. Which of the following best describes the objects motion?
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The object will rotate with constant angular acceleration
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A girl quickly moves to the center of a spinning merry go round, traveling along the radius of the merry go round. What can be said about the system's angular speed and moment of inertia?
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Moment of inertia decreases Angular speed increases
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If a bobs mass is doubled, approximately what will the new period be?
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T
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If the pendulum is taken into the orbiting space station what will happen to the bob?
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It will no longer oscillate because both the pendulum and the point to which it is attached are in free fall
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When a block is oscillating and the the kinetic energy is increasing then what how must the block be moving?
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Towards equilibrium
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Inelastic collisions- determine which object has a greater mass
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The objects whose initial velocity is closer to final velocity
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Kinetic energy inelastic collisions
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Not conserved
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Kinetic energy in elastic collision
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Conserved
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Center of mass in an inelastic collision
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Remains at a constant velocity (velocity = their combined velocity)
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Negative work's relationship to speed
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Decreasing speed indicates negative work
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Maximum Velocity of a wave
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A2pif
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Finding spring force of spring
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2pisqr(m/k)
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Loudness of sound
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Related to intensity
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Pitch of sound
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High or low frequency
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Beat frequency
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Equal to the difference in frequency of the two nodes that interfere
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Center of mass after collisions and explosions
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Same position relative to ground
