AP Physic test and answers

Assume the objects in the following diagrams have equal mass and the strings holding them in place are identical. In which case would the string be mostly likely to break

B

which block has the greatest speed just before hitting the ground

C

A mass m in three dimensional space is subjected to three forces F1,F2, and F3. F1 and F2 have the same magnitude, with F1, in the positive direction and F2 in the positive y direction. If the mass has an acceleration of 0 then which of the following statements is false?

The magnitude of F3 is the same as F1

A box slides to the right along a horizontal surface. which is true about the friction force?

it is the force that is proportional to the normal force that acts in opposition to the direction of motion

An object maintains its state of motion because is has

mass

A wooden box is first pulled across a horizontal steel plate. the box is then pulled across the same steel plate while the plate is inclined. how does the force required to overcome friction in the inclined case compare to the horizontal case?

the inclined case has less frictional force

A skydiver is falling at terminal velocity before opening her parachute. After opening parachute, she falls at a much smaller terminal velocity. how does the total upward force before she opens her parachute compare to the total upward force after she opens her parachute?

the upward force in both cases must be the same

which of the following statements are true regarding the coefficient of kinetic friction? (two answers)

1)Is in the direction of the motion 2)is specific to a combination of materials

50.0 N box is at rest on a horizontal surface. the coefficient of static friction between the box and the surface is 0.50 and the coefficient of kinetic friction between is 0.30. A horizontal 20.0N force is then exerted on the box. The magnitude of acceleration of the box is most nearly

1.0m/s

Which block takes the longest to reach the ground

B

which block has the greatest speed just before hitting the ground?

C

A block is held at rest against a wall by a force of magnitude F exerted at an angle θ from the horizontal, as shown in the figure above. Let Fg be the gravitational force exerted by Earth on the block, N be the normal force exerted by the wall on the block, and Ff be the frictional force exerted by the wall on the block. Which of the following statements about the magnitudes of the forces on the block must be true? (two answers)

FcosO=Fn FsinO= Fg +- Ff

A 6.0 kg block initially at rest is pushed against a wall by a 100N force shown the coefficient if kinetic friction is .30 while the coefficient of static friction is 0.50. what is true of the friction acting on the block after a time of 1 second?

Kinetic friction acts downward of the block

A homeowner pushes a lawn mower across a horizontal patch of grass with a constant speed by applying a force P. the arrows in the diagram correctly indicated the directions but not necessarily the magnitude of the various forces on the lawn mower. which of the following relations among the various force magnitudes, W,F,N,P is correct?

P>f and N>W

A block weight W is pulled along a horizontal surface at constant speed v by a force F, which acts at an angle of O with the horizontal, as shown to the left. the normal force exerted on the block by the surface has mangitude

W-FsinO

A box of unknown mass (m) slides down a plane inclined at an angle (O). The plane has a coefficient of friction (u). which of the following expressions would you use to calculate the rate of acceleration.

a=g(sinO - ucosO)

The graph at left shows the relationship between the mass of a number of rubber stoppers and their resulting weight on some far-off planet. The slope of the graph is a representation of the

acceleration due to gravity

A bus initially traveling north constant speed, as shown in the figure too the right. as the bus starts to make a turn to the left without changing speed, a passenger notices a box on the floor starts sliding toward the right side of the bus . Which of the following top views of the box, when correctly labeled, would best represent all of the horizontal forces exerted on the box as it starts sliding?

box with a arrow going left

Assume the elevator is moving at constant speed, and consider the bottom box on the stack that has two boxes mass 2m. Let Ffloor be the force exerted by gravity on the box and Fbox be the force exerted by the top box on the bottom box. Which of the following best represents the forces exerted on the bottom box.

box with one arrow going up and two arrows going down

Assume the elevator has upward acceleration a, and consider the stack that has teo boxes of mass M. what is magnitude of the force exerted on the top box by the bottom box?

m(a+g)

this position-time graph is typical of which type of motion

motion of an object with no net force acting on it

The cart of mass 10 kg shown above moves without frictional loss on a level table. A 10 N force pulls on the cart horizontal pulls on the cart to the right. At the same time, a 30N force at angle of 60 degree above the horizontal pulls the cart to the left. which of the following describes a manner in which this cart could be moving? (two answers)

moving left and speeding up moving right and slowing down

steve is standing facing forward in a moving bus. what force causes steve to move suddenly forward when the bus comes to an abrupt stop?

no forces were responsible for steve's movement

Susan pushes on box G that is next to box H, causing both boxes to slide along the floor as shown. The reaction force of susan's push is the

push of G against Susan

an empty wooden crate is slid across a warehouse. If the crate were filled, what would happen to the coefficient of kinetic fiction between the crate and the floor?

stay the same

A large tuck and a small car have a head-on collision. Which scenario is true?

the force of the trunk exerts on the car and the force that the car exert on the trunk are the same magnitude

A crate is on a horizontal frictionless surface. A force magnitude F is exerted on the crate at an angle O to the horizontal, as shown to the left, causing the crate to slide to the right. the surface a normal force of Fn on the crate.

the new normal force is less than Fn

The stack of boxes shown in figure above are inside an elevator that is moving upward. the masses of the boxes are given in terms of the mass M of the lightest box. how does the magnitude of the force exerted by the top box on the bottom box compare with the magnitude of the force exerted by the bottom box on the top box?

the two magnitudes are always equal in each of the stacks

Consider the forces on a child standing in an elevator. When is the normal force form the elevator equal to the gravitational force?

when the elevator moves up at the constant speed When the elevator is at rest