Q: A 7.8 kg object is acted on by two forces. One of the forces is $$18.0\ \mathrm{N}$$ acting toward the east. Which of the following forces will allow the object to accelerate at $$2.0\ \mathrm{m/s^2$}$$ toward the east?

$$2.4\ \mathrm{N}$$\ \text{west}$

Q: In the figure, a constant external force $$F = 300\ \mathrm{N} is $$applied to a $$20.0\ \mathrm{kg}$$ box, which is on a rough horizontal surface. While the force pushes the box a distance of $$8.00\ \mathrm{m}$$, the speed changes from $$0.500\ \mathrm{m/s} to$$ $$2.00\ \mathrm{m/s}. $$The work done by friction during this process is closest to:

$$-2.4 \times 10^3$\ \mathrm{J}$$

Q: During a collision with a wall, the velocity of a $$0.250\ \mathrm{kg}$$ ball changes from $$20.0\ \mathrm{m/s}$$ toward the wall to $$-16.0\ \mathrm{m/s}$$ away from the wall in $$0.010\ \mathrm{s}. $$What was the magnitude of the average force applied to the ball?

$$1.0 \times 10^3$\ \mathrm{N}$$

Question 1

A vector $$\vec{Z} is $$given by $$\vec{Z} = \vec{X} - \vec{Y}. If $$the magnitude of vector $$\vec{X} is 16 $$units and the magnitude of vector $$\vec{Y} is 7.0$\sqrt{2}$$ units, what is the magnitude of vector $$\vec{Z} if$$ $$\vec{X}$$ and $$\vec{Y}$$ are perpendicular?

Accepted Answer

$$15.0$$

Question 2

The scalar product of vector $$\vec{A} = 2.00\hat{i} + 2.00\hat{j}$$ and vector $$\vec{B} = 10\hat{i} is$$:

Accepted Answer

$$10.0$$

Question 3

A student starts moving with a constant velocity of $$2.0\ \mathrm{m/s}$$ for $$3.0\ \mathrm{s}$$, then comes to rest in $$1.0\ \mathrm{s}$$, and then stays at rest for $$2.0\ \mathrm{s}. $$Which of the following graphs best represents the velocity vs. time for this motion?

Accepted Answer

Graph (II)

Question 4

The acceleration of an object as a function of time is given by $$a(t) = (3.00\ \mathrm{m/s^3$})t$$, where $$t is in $$seconds. If the object is at rest at time $$t = 0.00\ \mathrm{s}$$, what is the velocity of the object at time $$t = 4.00\ \mathrm{s}$$?

Accepted Answer

$$24.0\ \mathrm{m/s}$$

Question 5

While an object is in projectile motion (with upward being positive) with no air resistance:

Accepted Answer

The horizontal component of its velocity remains constant and the vertical component of its velocity changes at a constant rate.

Question 6

A ball is tied to the end of a string of negligible mass. The ball is spun in a circle with a radius $$2.00\ \mathrm{m}$$ making 7.0 revolutions every 10.0 seconds. What is the magnitude of the acceleration of the ball?

Accepted Answer

$$38.7\ \mathrm{m/s^2$}$$

Question 7

A 7.8 kg object is acted on by two forces. One of the forces is $$18.0\ \mathrm{N}$$ acting toward the east. Which of the following forces will allow the object to accelerate at $$2.0\ \mathrm{m/s^2$}$$ toward the east?

Accepted Answer

$$2.4\ \mathrm{N}$$\ 	ext{west}$

Question 8

You push downward on a box at an angle $$25^\circ$$ below the horizontal with a force of $$75.0\ \mathrm{N}. If $$the box is on a flat horizontal surface for which the coefficient of static friction with the box is $$0.36$$, what is the mass of the heaviest box you will be able to move?

Accepted Answer

$$20.4\ \mathrm{kg}$$

Question 9

A $$0.20\ \mathrm{kg}$$ hockey puck is launched up a ramp that is inclined at a $$30^\circ$$ angle. The coefficient of kinetic friction between the hockey puck and the ramp is $$\mu_k = 0.30. $$The puck's initial speed is $$4.0\ \mathrm{m/s}. $$How long does it take for the hockey puck to come to a momentary stop (before it slides back down again)?

Accepted Answer

$$0.81\ \mathrm{s}$$

Question 10

An object of mass $$2.0\ \mathrm{kg}$$ moves along the x-axis. The potential energy curve as a function of position along the x-axis is shown in the figure. If the kinetic energy of the object at the origin is $$12.0\ \mathrm{J}$$, what will be its kinetic energy at $$x = 2.0\ \mathrm{m} if$$ $$U(2.0\ \mathrm{m}) = 4.0\ \mathrm{J}$$ and $$U(0) = 0$$?

Accepted Answer

$$8.0\ \mathrm{J}$$

Question 11

In the figure, a constant external force $$F = 300\ \mathrm{N} is $$applied to a $$20.0\ \mathrm{kg}$$ box, which is on a rough horizontal surface. While the force pushes the box a distance of $$8.00\ \mathrm{m}$$, the speed changes from $$0.500\ \mathrm{m/s} to$$ $$2.00\ \mathrm{m/s}. $$The work done by friction during this process is closest to:

Accepted Answer

$$-2.4 	imes 10^3$\ \mathrm{J}$$

Question 12

Two objects of the same mass move along the same line in opposite directions. The first mass is moving at $$+4.0\ \mathrm{m/s}$$, the second at $$-6.0\ \mathrm{m/s}. $$After they collide and stick together, what is the speed of the second mass before the collision?

Accepted Answer

$$6.0\ \mathrm{m/s}$$

Question 13

During a collision with a wall, the velocity of a $$0.250\ \mathrm{kg}$$ ball changes from $$20.0\ \mathrm{m/s}$$ toward the wall to $$-16.0\ \mathrm{m/s}$$ away from the wall in $$0.010\ \mathrm{s}. $$What was the magnitude of the average force applied to the ball?

Accepted Answer

$$1.0 	imes 10^3$\ \mathrm{N}$$

Question 14

A machinist uses a grinding wheel that is spinning at an angular velocity of $$25\ \mathrm{rad/s}. $$Upon completing her job, she shuts down the power. The wheel decelerates uniformly at $$1.5\ \mathrm{$$rad/s^2$$}$$ until the wheel stops. What is the time interval of angular deceleration?

Accepted Answer

$$16.7\ \mathrm{s}$$

Question 15

A uniform solid disk of radius $$1.00\ \mathrm{m}$$ and mass $$2.50\ \mathrm{kg}$$ rolls without slipping to the bottom of an inclined plane. The angular velocity of the disk is $$3.35\ \mathrm{rad/s} at $$the bottom. What is the height of the plane? (The moment of inertia of a solid disk is $$I = \frac{1}{2}MR^2$.)

Accepted Answer

$$0.57\ \mathrm{m}$$

Question 16

A potter's wheel, with rotational inertia $$4.0\ \mathrm{kg\cdot m^2$}$$, is spinning freely at $$40\ \mathrm{rpm}. $$The potter drops a lump (clay) of mass $$2.0\ \mathrm{kg}$$, which sticks at $$0.20\ \mathrm{m}$$ from the rotational axis. What is the subsequent angular speed of the wheel and clay in $$\mathrm{rpm}$$?

Accepted Answer

$$31.4$$

Question 17

A light triangular plate (4.0 kg) is in a horizontal plane. Three forces, $$F_1 = 6.0$$\ \mathrm{N}$$, F_2$ = 9.0\ \mathrm{N}$$, and $$F_3 = 7.0$$\ \mathrm{N}$$, act on the plate, which is pivoted about a vertical stem through point O. The sum of the torques about the vertical axis through point O, acting on the plate due to the forces, is closest to:

Accepted Answer

$$4.4\ \mathrm{Nm}$$

Question 18

A traffic light weighing $$100\ \mathrm{N} is $$supported by two ropes as shown in the figure. The tensions in the ropes are closest to:

Accepted Answer

$$60.5\ \mathrm{N}$$

Question 19

While spinning down from $$500\ \mathrm{rpm} to $$rest, a solid uniform flywheel does $$5.1\ \mathrm{kJ} of $$work. If the radius of the disk is $$1.2\ \mathrm{m}$$, what is its mass?

Accepted Answer

$$8.2\ \mathrm{kg}$$

Question 20

A $$2.00\ \mathrm{m}$$ rod of negligible mass connects two very small objects at its ends. The mass of one object is $$0.50\ \mathrm{kg}$$ and the mass of the other is unknown. The center of mass of the system is $$1.20\ \mathrm{m}$$ from the $$0.50\ \mathrm{kg}$$ mass object. What is the mass of the other object?

Accepted Answer

$$0.83\ \mathrm{kg}$$

PHYS 2204 – Final Exam Study Notes: Mechanics, Energy, and Rotational Motion

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