Physics: Chapter 6 – Flashcards

Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct? A) Both do zero work B) Both do positive work, but person X does four times the work of person Y. C) Both do the same amount of positive work D) Both do positive work, but person X does one-half the work of person Y. E) Both do positive work, but person X does twice the work of person Y.

If the force on an object is in the negative direction, the work it does on the object must be A) positive B) negative C) the work could be either positive or negative, depending on the direction the object moves

Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on the car. A) Jerry does 50% more work than Joel B) Joel does 50% more work than Jerry. C) Joel does 25% more work than Jerry. D) Joel does 75% more work than Jerry. E) Neither of them does any work

You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down. A) The work is positive on the way up and negative on the way down. B) The work is negative on the way up and positive on the way down. C) The work is negative on the way up and on the way down because gravity is always downward. D) The work is positive on the way up and positive on the way down.

A 35-N bucket of water is lifted vertically 3.0 m and then returned to its original position. How much work did gravity do on the bucket during this process? A) 180 J B) 900 J C) 90 J D) 0 J E) 45 J

A 4.0 kg object is moving with speed of 2.0 m/s. A 1.0 kg object is moving with speed 4.0 m/s. Both objects encounter the same constant breaking force, and are brought to rest. Which object travels the greater distance before stopping? A) the 4.0 kg object B) the 1.0 kg object C) Both objects travel the same distance. D) It cannot be determined from the information given

You and your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you and your friend, after you both reach the top. A) It is impossible to tell, since the distances you both traveled are unknown B) Your gravitational potential energy is greater than that of your friend, because you traveled a greater distance in getting to the top. C) Your friend's gravitational potential energy is greater than yours, because he got to the top faster. D) Both of you have the same amount of gravitational potential energy at the top. E) It is impossible to tell, since the times you both took are unknown.

When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed should you throw it up vertically so it will go twice as high? A) 16 V B) 4 V C) 2 V D) 8 V E) Square root of V

Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when they hit the ground A) the heavier one will have four times the kinetic energy of the lighter one. B) both will have the same kinetic energy C) the heavier one will have one-fourth the kinetic energy of the lighter one. D) The heavier one will have half the kinetic energy of the lighter one. E) The heavier one will have twice the kinetic energy of the lighter one

Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph? A) 0 mph to 30 mph B) 50 mph to 60 mph C) It is the same in both cases

Two frisky otters slide down frictionless hillsides of the same height but different slopes. The slope of the hill of otter 1 is 30°, while the slope of the hill of otter is 2 is 60°. If both start from rest, which otter is moving faster when she reaches the bottom of her hill? A) Otter 1 is moving faster. B) Otter 2 is moving faster. C) The otter that took the shorter time is moving faster. D) The heavier otter is moving faster, no matter which hill she used. E) Both otters have the same speed at the bottom

A 3.0-kg brick rests on a perfectly smooth ramp inclined at 34° above the horizontal. The brick is kept from sliding down the plane by an ideal spring that is aligned with the surface and attached to a wall above the brick. The spring has a spring constant (force constant) of 120 N/m/ By how much does the spring stretch with the brick attached? A) 36 cm B) 14 cm C) 240 cm D) 360 cm E) 24 cm

An ornament of mass 40.0 g is attached to a vertical ideal spring with a force constant (spring constant) of 20.0 N/m/ The ornament is then lowered very slowly until the spring stops stretching. How much does the spring stretch? A) 0.200 m B) 0.800 m C) 0.00200 m D) 0.0816 m E) 0.0196 m

Matthew pulls his little sister Sarah along the horizontal ground in a wagon. He exerts a force on the wagon of 60.0 N at an angle of 37° above the horizontal. If he pulls her a distance of 12.0 m, how much work does Matthew do? A) 575 J B) 433 J C) 720 J D) 185 J

A 1000-kg car experiences a new force of 9500 N while slowing down from 30 m/s to 15.9 m/s. How far does it travel while slowing down? A) 31 m B) 41 m C) 34 m D) 37 m

The kinetic friction force that a horizontal surface exerts on a 60.0-kg object is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop? A) 30.0 m B) 750 m C) 375 m D) 15.0 m

A sled having a certain initial speed on a horizontal surface comes to rest after traveling 10 m. If the coefficient of kinetic friction between the object and the surface is 0.20, what was the initial speed of the object? A) 8.9 m/s B) 9.8 m/s C) 3.6 m/s D) 7.2 m/s E) 6.3 m/s

How much work is required to stretch an ideal spring of spring constant (force constant) 40 N/m from x=0.20m to x=0.25m if the unstretched position is at x=0.00m? A) 1.3 J B) 0.050 J C) 0.80 J D) 0.45 J

In the figure, a ball hangs by a very light string. What is the minimum speed of the ball at the bottom of its swing (point B) in order for it to reach point A, which is 1.0 m above the bottom of the swing? A) 4.9 m/s B) 2.2 m/s C) 3.1 m/s D) 4.4 m/s

What is the net power needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s to 40.0 m/s in 4.00 seconds? A) 14.0 kW B) 10.0 kW C) 275 kW D) 140 kW E) 100 kW