Question 1

A car drives over a hilltop that has a radius of curvature $$r = 0.120\ \mathrm{km} at $$the top of the hill. At what speed $$v$$ would the car be traveling when its tires just barely lose contact with the road when the car is at the top of the hill?

Accepted Answer

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

Question 2

A child on a swing reaches the lowest point in her swing. If her acceleration is upward at $$9.8\ \mathrm{m/s^2$}$$, what is the tension in the rope compared to her weight?

Accepted Answer

The tension in the rope is greater than her weight.

Question 3

When you ride in a car that is making a left turn, you feel as though you are being thrown to the right side of the car. Which of Newton's laws describes this behavior?

Accepted Answer

Newton's 1st Law

Question 4

A box of mass $$m is $$placed atop a postal scale sitting on the floor of an elevator. If the scale reads a value of $$F_s$$, how fast is the elevator accelerating? Assume the elevator is accelerating up when considering signs.

Accepted Answer

$$F_s = m (g + a)$$

Question 5

Which of the following is always equal to your mass?

Accepted Answer

None of the above

Question 6

A block of mass $$m is at $$rest on an inclined plane that makes an angle $$	heta$$ with the horizontal. The force of static friction $$f_s$$ must be such that:

Accepted Answer

$$f_s = m g \sin 	heta$$

Question 7

A $$4.0\ \mathrm{N}$$ force is applied horizontally on a book that weighs $$20\ \mathrm{N}$$ that is resting on a tabletop. If $$\mu_s = 0.10$$ between book and table, find the force of static friction on the book.

Accepted Answer

$$2.0\ \mathrm{N}$$

Question 8

The centripetal force required to travel in a circular trajectory:

Accepted Answer

Can change the velocity of the object.

Question 9

In Figure 5-1, masses $$m_1$$ and $$m_2$$ are such that $$m_1$$ \u003e $$m_2$$ and they lay on a level, frictionless surface. We can apply a horizontal force $$\vec{F}$$ either from the left or from the right. The contact force between masses $$m_1$$ and $$m_2 is$$:

Accepted Answer

Larger when $$\vec{F} is $$applied from the right.

Question 10

The SI units for the spring constant $$k$$ are equivalent to:

Accepted Answer

$$\mathrm{N/m}$$

Question 11

A force of $$30\ \mathrm{N}$$ stretches a spring $$0.73\ \mathrm{m}$$ from equilibrium. What is the value of the spring constant $$k$$?

Accepted Answer

$$41\ \mathrm{N/m}$$

Question 12

Two masses, $$m_1$$ and $$m_2$$, are connected to each other as shown in Figure 6-5. Mass $$m_1$$ slides without friction on the table surface. Both masses have acceleration of magnitude $$a as $$shown. How does the tension in the string compare to the weight, $$m_2 g$, of mass m_2$?

Accepted Answer

The tension is smaller than $$m_2 g$.

Question 13

In the mathematical definition for work, the best way to describe the formula $$W = \vec{F} \cdot \vec{d} is$$:

Accepted Answer

It is the component of the force vector parallel to the line defined by the displacement vector.

Question 14

If you push hard against a stationary brick wall, the amount of work you do on the wall:

Accepted Answer

Remains constant at zero.

Question 15

Does the centripetal force acting on an object do work on the object?

Accepted Answer

No, because the force and the displacement of the object are perpendicular.

Question 16

Kinetic energy is a scalar quantity.

Accepted Answer

True

Question 17

You drop a $$6.0\ \mathrm{kg}$$ ball from $$2.0\ \mathrm{m}. It $$rebounds to $$1.5\ \mathrm{m}. $$How much energy is lost to heating and sound production?

Accepted Answer

$$29\ \mathrm{J}$$

Question 18

A spring is compressed a distance $$d$$ and is used to launch a mass vertically to a height $$h$$ above its starting position. The experiment was repeated with the same mass but this time the height was twice the height achieved in the first experiment. How far was the spring compressed in the second experiment?

Accepted Answer

$$\sqrt{2} d$$

Question 19

The rate at which work is done is equivalent to which of the following?

Accepted Answer

Power

Question 20

Refer to Figure 6-11. Block A has a mass of $$3.0\ \mathrm{kg}$$ and rests on a smooth table and is connected to block B, which has a mass of $$2.0\ \mathrm{kg}$$, after passing over an ideal pulley, as shown. Block B is released from rest. What is the acceleration of the masses?

Accepted Answer

$$3.22\ \mathrm{m/s^2$}$$

Fundamental Concepts in Mechanics: Forces, Energy, and Motion

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