Physics Chapter 10 Test

How much kinetic energy does a X-kg stone have if it is thrown at Y-m/s?

1/2(X)(Y squared)

How much work must be done by frictional forces in slowing a X-kg car from Y-m/s to rest?

1/2mv sqaured ... 1/2(X)(Y squared)

Which one has larger kinetic energy: a 5-kg object moving at 10 m/s or a 2.5-kg object moving at 20 m/s?

2.5 kg moving at 20 m/s (use 1/2mv squared)

Three cars (car A, car B, and car C) are moving with the same speed and slam on their brakes. The most massive car is car C, and the least massive is car A. If the tires of all three cars have identical coefficients of kinetic friction with the road surface, for which car is the amount of work done by friction in stopping it the greatest?

Car C bcit has more KE and the biggest force

If the work done to stretch an ideal spring by X-cm is Y-J, what is the spring constant (force constant) of this spring?

K = 2Y/x squared

If a stone is dropped with an initial gravitational potential energy of 100 J but reaches the ground with a kinetic energy of only 75 J, is this a violation of the principle of conservation of energy?

No (lost to air resistance)

You carry a X-kg bag of groceries above the ground at constant speed across a Y-m room. How much work do you do on the bag in the process?

No 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.

The work is negative on way up and positive on way down

Three cars (car A, car B, and car C) are moving with the same speed and slam on their brakes. The most massive car is car C, and the least massive is car A. If the tires of all three cars have identical coefficients of kinetic friction with the road surface, which car travels the longest distance to skid to a stop?

They all travel same distance in stopping

Maurice pulls his little sister Connie along the horizontal ground in a wagon. He exerts a force on the wagon of X-N at an angle of Y° above the horizontal. If he pulls her a distance of Z-m, how much work does Maurice do?

W = Fdcos (angle) .... W = X(Z)cos (Y degrees)

How much work would a child do while pulling a X-kg wagon a distance Y-m of with a Z-N force?

W = ZY

Person X pushes twice as hard against a stationary brick wall as person Y. Which one does more work?

both do zero work

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.

both have same amount at the top

A 8.0 kg object is moving with speed 3.0 m/s. A 2.0 kg object is moving with speed 6.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?

both objects travel the same distance

In a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the cue ball had originally. Both balls have the same mass. This type of collision is

elastic

A stone is held at a height h above the ground. A second stone with four times the mass of the first one is held at the same height. The gravitational potential energy of the second stone compared to that of the first stone is

four times as much

Suppose a uniform solid sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The linear velocity of the sphere at the bottom of the incline depends on

height, g

If the force on an object is in the negative direction, the sign work it does on the object must be?

it could be either depending on which way the object moves

Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?

lighter one

If the units of your answer are kg ∙ m2/s3, which of the types of quantities could your answer be?

power (watts)

Suppose a solid uniform sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The angular velocity of the sphere at the bottom of the incline depends on

radius, height of incline, g

A disk, a hoop, and a solid sphere are released at the same time at the top of an inclined plane. They are all uniform and roll without slipping. In what order do they reach the bottom?

sphere, disk, hoop

Two objects of different mass have equal, non-zero kinetic energies. Which object has the greater magnitude momentum?

the heavier object

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 how will their kinetic energies compare?

the heavier one will have twice the KE of the lighter one

A truck has twice the mass of a car and is moving with twice the speed of the car. If Kt and Kc refer to the kinetic energies of truck and car respectively, compare their kinetic energy values:

trucks is 8 times greater

A X-N bucket of water is lifted vertically Y m and then returned to its original position. How much work did gravity do on the bucket during this process?

0 Work because it returns to it's original position

When you drop a pebble from height H, it reaches the ground with kinetic energy K if there is no air resistance. From what height should you drop it so it will reach the ground with twice as much kinetic energy?

2H

Which requires more work, increasing a car's speed from 0 m/s to 20 m/s or from 30 m/s to 40 m/s?

30 - 40 (use 1/2 mv squared final minus 1/2mv squared initial)

You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

4 times further

When you drop a pebble from height H, it reaches the ground with speed V if there is no air resistance. From what height should you drop it so it will reach the ground with twice speed?

4H - (square 2 bc twice) Another Example: if it was triple speed it would be 9H for example

Jill does three times as much work as Jack does and in half the time. Jill's power output is...

6 times as much as Jacks

A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill with no air resistance. Which object rises to a greater height?

They both slide to exactly the same height

A crane lifts a X-kg steel beam vertically upward a distance of Y-m How much work does the crane do on the beam if the beam accelerates upward at Z m/s2? Neglect frictional forces.

W = ma x d ????