Question 1 You toss a ball straight upwards and it reaches a maximum height H

Question 1

You toss a ball straight upwards and it reaches a maximum height H. Which of the formulas below gives the correct time t that the ball will take to fall back in your hand?

 0 t=8h/g

0 Cannot answer this question if the mass m of the ball is not given

0  t =√ 2h/g

0 t=gh

0 t= √ 8h/g

Question 2

If A+ B = si+ 5j and "A –B^- =i+j, then A must be:

0 A=2i+ 3j

OA= -2i —3j

O A=4i+6j

O A= -4i +4j

O A^-=o^-

Question 3

An object, moving with constant speed V around a circular trajectory of radius R, has a centripetal acceleration a_c. What should be the object's speed so that the acceleration is 8ac when the radius is 2R?

0 V+ 4

0 2V

0 V/2

0 4v

0 e. V/4

Question 4

In a building, elevator #1 is moving upwards with constant speed V1, In the building next door, elevator #2 is moving down with constant speed V2. V2 is larger then V1. What can you say about the net forces _F1net and _F2net on each elevator?

0 _F1net and _F2net both point upwards

0 _F1net points up and _F2net points down, with [_F1net] and [_F2net]

0 _F1net and _F2net are both zero

0 _F1net points up and _F2net points down, with [_F1net] >[ _F2net]]

0 _F1net points up and _F2net points down, with [_F1net] <[ _F2net]]

Question 5

A set of four boxes, each of mass m, is assembled as shown in the figure:

A constant force F is applied to box A, as shown. Static friction between the boxes prevents them from sliding relative to each other, and the faction between boxes and ground is negligibly small. Therefore, the force by box A on box B is equal to:

O F

O 3F/4

O F/2

O 2F

O F/3

Question 6

Two blocks of masses M1 and M2 are connected by a string as shown in the figure. The pulley is frictionless and has negligible mass. What is the correct formula for the friction coefficient µk between M1 and the horizontal surface so that the blocks move with constant velocity?

0 µk =M1/M2

0 µk =M2/M1

0 µk =M2g

0 µk =M1g

0 µk =0

Question 7

You kick a 1.00 kg brick sitting on the sidewalk (ouch!) and the brick slides 2.00 to before coming to a stop. The kinetic friction coefficient between brick and sidewalk is µk= 0.64. The work done by your foot on the brick is...

 0-12.5J

0 12.5J

0.... impossible to calculate because the force between your foot and the brick is not known.

0 ... zero

Question 8

In the carnival ride below, the car (of total mass M) is pushed by a spring so that, starting from rest, it reaches a maximum speed V₀ as it separates from the spring. The car moves without friction along the horizontal track, then enters the loop (radius R) and reaches the top where its speed is V₁.

Which of the following formulas correctly relates V₀ and V₁?

0 V₀² =V₁²+4Rg

0 V₀² =V₁² - 4Rg

0 V₀² =V₁² + 2Rg

0 V₀² =V₁² - 2Rg

0 V₀ =2V₁Rg

Question 9

One end of a spring (of spring constant K) is attached to the ceiling and an object of mass m is attached to the other end. The spring stretches down by a distance x from its relaxed position when the object just hangs at rest. If the total potential energy of the system is zero when the spring is at its relaxed position, then when the spring is stretched the total potential energy U_t of the system and the potential energy U_s of the spring are:

0 U_t<0and U_s<0

0 U_t < 0 and U_s>0

0 U_t > 0 and U_s<0

0 U_t = 0 and U_s=0

0 U_t = 0 and U_s>0

Question 10

Three balls are placed along a straight line and are free to move without any friction. The balls have equal sizes, balls 2 and have the same mass, but ball 1 is heavier. Only ball 1 is initially moving (see figure). All collisions between the balls are elastic and one-dimensional. After all collisions have taken place, what can you say about the balls?

O Ball 1 is moving to the left, balls 2 and 3 to the right

O Ball 1 is moving to the left, ball 2 is at rest, ball 3 is moving to the right

O All three of them are moving to the right

O Balls 1 and 2 are at rest, ball 3 is moving to the right

O Balls 1 and 2 are moving to the left, ball 3 to the right

Question 11

Two cars, of masses M1 and M2, crash head-to-head and get stuck to each other. If the friction with the pavement during the collision is negligible and the 2-car combination has zero kinetic energy just after the collision, what can you say about the car momenta P1 and P2 before the collision?

0 P₂ =P₁

0 P₂ = 0 and P₁=0

0 None of the other answers is correct

0 P₂= -P₁

Question 12

Just before crashing into each other, two objects have non-zero kinetic energies K₁ and K₂. Just after the collision, can the total kinetic energy be zero?

0 No, never.

0 Yes, but not due to any of the reasons above

0 Yes, but only if the objects have equal and opposite velocities before the collision

0 Yes, as long as K₁ = K₂

0 Yes, but only if the objects have equal and opposite momenta before the collision

Question 13

If the angular speed of a rotating object is given by w(t) =3t rad/s, then the change in angle ? ? between t=3s and t=5s is:

O 12 rad

O 6 rad

O 24 rad

O 3 rad

O 18 rad

Question 14

A disk is able to spin around any of the three coordinate axis (all of which pass through the center of the disk). What can you say about the moments of inertia I_x, l_y and I_z of the disk relative to each axis?

0 1_y = I_x = l_z

0 l_y < l_x < l_z

0 l_y > I_x > l_z

0 l_y > I_x = I_z

0 l_y < I_x = l_z

Question 15

When a disk of mass m rolls down a slope without slipping, it experiences a net force F₁ net. If then you grease the slope so that the disk now slides as it rolls down, the net force _F2net on the disk must such that:

0 F₁ net > _F2net

0 F₁ net < _F2net

0 F₁ net + _F2net = Mg

0 F₁ net - _F2net = Mg

0 F₁ net = _F2net

Question 16

A stick of mass m and length L is held horizontally by two strings, one at each end. You then cut the sting on the left end. The sticks start to rotate about its right end. What is the initial angular acceleration of the stick (just after you cut the string)?

(g is the acceleration of gravity)

0 3g/2L

0 mg

0 3g/L

0 3mg/2L

0 g

Question 17

If an object is in static equilibrium, which one of the following statements does not have to be always true:

0 The object has zero acceleration

0 The net force on the object is zero

0 The net torque on the object is zero

0 The object has zero velocity

0 The object's center of mass may be used as the origin of an inertial reference frame

Question 18

Two objects hang from each end of a 1.2 m long road. The mass of the object on the left is 2.5 kg and the mass of the object on the right is 7.5 kg (the rod is much lighter than either object). Where can you hold the rod so that it does not try to tip in either direction? X=0 at the left end of the road.

O x= 0.9m

O x= 0.6m

O x=0.5m

O x= 0.4m

O x=0.3m

Question 19

A person sits at the center of a flat disk, which rotates freely (i.e., no friction, no external torques) around its axis. That person then walks to the edge of the cylinder and stays there. What happens to this system's kinetic energy, angular momentum, and moment of inertia during this process?

O Kinetic energy increases, angular momentum is unchanged, and moment of inertia increases O Kinetic energy increases, angular momentum increases, and moment of inertia increases

O Kinetic energy decreases, angular momentum is unchanged, and moment of inertia decreases

O Kinetic energy decreases, angular momentum is unchanged, and moment of inertia increases

O Kinetic energy decreases, angular momentum decreases, and moment of inertia decreases

Question 20

When can you use the equation v=v₀ + at when solving a simple harmonic motion problem?

O Only when the mass is moving vertically

O Never

O Always

O Only when v₀ = 0