Question 1

A 10.0 kg object is acted upon by the forces shown in the diagram (see Image 1). What is the x-component of the object's acceleration, $$a_x (in m/s$^2$$)?

Use $$\sum F_x = m a_x$$ and resolve the 5.0 N force into components.

Accepted Answer

$$0.25$$

Question 2

A 10.0 kg object is acted upon by the forces shown in the diagram (see Image 1). What is the y-component of the object's acceleration, $$a_y (in m/s$^2$$)?

Use $$\sum F_y = m a_y$$ and resolve the 5.0 N force into components.

Accepted Answer

$$-0.25$$

Question 3

Two friends slide a 175 kg box across the floor. One pushes with 225 N and the other pulls with 310 N. The box moves at constant speed. What is the coefficient of kinetic friction between the box and the floor?

Use $$f_k = \mu_k N$$ and $$N = mg.$$

Accepted Answer

$$0.32$$

Question 4

A cart of mass $$m is at $$rest. A force $$F is $$applied for time $$\Delta t$$, giving it speed $$v. If $$the same force is applied for the same time to a cart of mass $$4m$$, what is its final speed?

Accepted Answer

$$\frac{1}{2}v$$

Question 5

Refer to Image 3. Two 5 kg masses hang at rest over frictionless pulleys with a massless string and a spring scale. What does the spring scale read?

Accepted Answer

$$5 kg$$

Question 6

A car turns a corner on a banked road. Which free-body diagram (see Image 4) correctly represents the forces acting on the car?

Accepted Answer

C

Question 7

A block on a string spins in a horizontal circle on a frictionless table counterclockwise. The block is held by the tension of the string (TA to TD). Which one is correct about the tensions?

Accepted Answer

TA = TC \u003e TD \u003e TB

Question 8

An object in a circular orbit near the surface of a planet (gravity: $$6.7\ \mathrm{m/s^2$}$$; radius: $$9,800\ \mathrm{km}) is $$experiencing uniform circular motion. What is its orbital velocity?

Use $$v = \sqrt{g r}.$$

Accepted Answer

$$8\ \mathrm{km/s}$$

Question 9

A mosquito runs head-on into a truck. Which statement is true during the collision?

Accepted Answer

The mosquito exerts the same force on the truck as the truck exerts on the mosquito.

Question 10

A 1600 kg car takes a 50-m-radius unbanked curve at 15 m/s. What is the size of the friction force on the car?

Use $$f = m \frac{v^2$}{r}.$$

Accepted Answer

$$7200$$

Question 11

A space station is constructed as a 1200-m-diameter cylinder that rotates about its axis. What rotation period will provide 'normal' gravity ($$g = 9.8\ \mathrm{m/s^2$}$$)?

Use $$a_c = \$$omega^2$$ r = g$$ and $$T = \frac{2\pi}{\omega}.$$

Accepted Answer

$$49$$\ s

Question 12

A 5.0 N force acts at $$20^\circ$$ above the negative x-axis (see Image 1). What is the x-component of this force?

Use $$F_x = F \cos	heta.$$

Accepted Answer

$$-4.7 N$$

Question 13

A 5.0 N force acts at $$20^\circ$$ above the negative x-axis (see Image 1). What is the y-component of this force?

Use $$F_y = F \sin	heta.$$

Accepted Answer

$$1.7 N$$

Question 14

A block of mass $$m is $$spun in a horizontal circle of radius $$r at $$constant speed $$v. $$What is the tension in the string?

Use $$T = m \frac{v^2$}{r}.$$

Accepted Answer

$$T = m \frac{v^2$}{r}$$

Question 15

A 175 kg box is pulled with a total force of 535 N and moves at constant speed. What is the normal force acting on the box?

Use $$N = mg.$$

Accepted Answer

$$1715 N$$

Question 16

A car of mass $$m$$ moves in a circle of radius $$r at $$speed $$v on a $$flat road. What is the minimum coefficient of friction required to prevent slipping?

Use $$\mu = \frac{v^2$}{g r}.$$

Accepted Answer

$$\mu = \frac{v^2$}{g r}$$

Physics with Calculus: Forces, Motion, and Circular Dynamics Study Guide

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