Question 1

A projectile is launched from the ground at an angle and collides head-on with another projectile launched horizontally from a height, as shown in the diagram. The collision occurs exactly halfway between their starting points. Which graph (a, b, c, or d) best represents the vertical component of the velocity $$v_y of $$the projectile fired from the ground, up to the moment just before the collision?

Accepted Answer

c. The graph where $$v_y$$ decreases linearly throughout the flight, with no abrupt change at the collision.

Question 2

Refer to the velocity vs. time graphs for two carts, A and B, that interact only with each other (other than gravity and the normal force). Cart A has twice the mass of cart B. Which graph correctly represents their possible motions during and after their interaction?

Accepted Answer

The graph where cart A's velocity changes less than cart B's, and both change direction after the interaction.

Question 3

A block slides around a frictionless loop-the-loop. At point A (halfway up the loop) and point B (at the top), scales measure the normal force exerted by the block. Which of the following is true about the scale readings?

Accepted Answer

Scale A reads $$2N$$ more than scale B.

Question 4

A block is connected to two massless strings over pulleys as shown. The maximum mass $$m$$ can be hung from hook #1 without moving the block. If $$m is $$hung from hook #1, what is the maximum mass that can be hung from hook #2 without causing the block to accelerate?

Accepted Answer

$$m/2$$

Question 5

A force $$F = 10\,\mathrm{N} is $$applied tangentially to the end of a thin, solid semicircular arc of radius $$r = 4\,\mathrm{m} as $$shown. What is the magnitude of the torque about the pivot?

Accepted Answer

$$120\,\mathrm{Nm}$$

Question 6

A block starts from rest and is subjected to a force along the $$x-$$axis whose time dependence is shown in the force vs. time graph. Which power vs. time graph (a, b, c, or d) correctly represents the power delivered to the block?

Accepted Answer

b. The power graph is positive and increases in the second interval.

Question 7

A system of four balls of varying masses is shown, with a force $$F$$ applied to one ball. Which additional force(s) (A, B, C, D) must be applied to ensure the center of mass does not accelerate?

Accepted Answer

D, B, or C only

Question 8

Three uniform blocks are at rest side-by-side on a frictionless floor, separated by loaded springs. After both springs unload, the center block is stationary while the outer blocks move apart. What can be concluded about the system?

Accepted Answer

The outer blocks are not moving at the same speed, and the system center of mass is at rest at the center of the middle block.

Question 9

A block of mass $$M$$ slides toward a stationary block of mass $$m on a $$frictionless surface. After the collision, block $$M$$ stops and block $$m$$ moves off. Which type of collision preparation allows this result?

Accepted Answer

Spring-loaded ($$\Delta KE \u003e 0)$$

Question 10

A potential energy function is given by $$U(x, y, z) = \alpha x^3$ y - \beta x + U_0$. Which statement is false?

Accepted Answer

All of these statements are false.

Question 11

Refer to the potential energy curve $$U(x)$$ shown, with total energy $$E_{tot}$$ indicated. As the object moves from position $$A to$$ $$Z$$, at which position is the power delivered to the object the greatest?

Accepted Answer

At position $$B$$

Question 12

A thin, solid semicircular arc of radius $$r is $$acted on by a force $$F at $$the end as shown. If each grid square is $$1\,\mathrm{m}$$, and $$F = 10\,\mathrm{N}$$, what is the torque about the pivot?

Accepted Answer

$$120\,\mathrm{Nm}$$

Question 13

Two blocks are hung from massless pulleys as shown, with the larger pulley having twice the radius of the smaller one. If the string does not slip, how are the rotational velocities $$\$$omega_1$$ and $$\$$omega_2 of $$the pulleys related?

Accepted Answer

$$\$$omega_1$$ = 2\$$omega_2$$

Question 14

A uniform circular piece of plywood of mass $$M$$ and radius $$R$$ has an equilateral triangle cut out and reattached as shown. What is the rotational inertia about the pivot point?

Accepted Answer

$$\frac{3}{2}MR^2$

Question 15

The density of the object shown is not uniform, and its center of mass is at point $$C. $$Which statement is true about the rotational inertias around axes perpendicular to the page at the various points?

Accepted Answer

The two largest rotational inertias are around points $$A$$ and $$E.$$

Physics Study Guide: Kinematics, Dynamics, and Energy Concepts

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