Q: The average velocity of an object is given by which of the following equations?

$$v_{\text{avg}} = \frac{\Delta x}{\Delta t}$$

Q: Which of the following is the correct expression for instantaneous acceleration?

$$a = \lim_{\Delta t \to 0} \frac{\Delta v}{\Delta t}$$

Q: A car travels the first half of a trip at $$10\ \mathrm{km/h}$$ and the second half at $$90\ \mathrm{km/h}. $$What is the average speed for the entire trip?

$$v_{\text{avg}} = 18\ \mathrm{km/h}$$

Question 1

Which of the following best describes the difference between displacement and distance for an object thrown straight up and caught at the same point?

Accepted Answer

Displacement is zero, while distance is twice the height.

Question 2

A car moves from position $$x_i = 30\ \mathrm{m} to$$ $$x_f = 52\ \mathrm{m}. $$What is its displacement?

Accepted Answer

$$\Delta x = 22\ \mathrm{m}$$

Question 3

Which of the following is a vector quantity?

Accepted Answer

Velocity

Question 4

The average velocity of an object is given by which of the following equations?

Accepted Answer

$$v_{	ext{avg}} = \frac{\Delta x}{\Delta t}$$

Question 5

A tourist runs at $$4.0\ \mathrm{m/s}$$ toward a car, with a bear $$26\ \mathrm{m}$$ behind running at $$6.0\ \mathrm{m/s}. $$What is the maximum distance $$d$$ the tourist can be from the car and still reach it safely?

Accepted Answer

$$d = 52\ \mathrm{m}$$

Question 6

Which kinematic equation would you use to solve for displacement when you know initial velocity, acceleration, and time, but not final velocity?

Accepted Answer

$$\Delta x = v_0$ t + \frac{1}{2} a t^2$

Question 7

A ball is thrown upward with an initial velocity of $$20.0\ \mathrm{m/s}$$ from a height of $$50.0\ \mathrm{m}. $$What is the acceleration acting on the ball during its flight (neglecting air resistance)?

Accepted Answer

$$a = -9.80\ \mathrm{m/s}^2$$

Question 8

Which of the following statements about free fall is correct?

Accepted Answer

All objects in free fall near Earth's surface accelerate downward at the same rate, regardless of mass.

Question 9

A rocket accelerates upward at $$29.4\ \mathrm{m/s}^2$$ for $$4.00\ \mathrm{s}$$, then runs out of fuel and continues upward under gravity alone. What is its velocity at the end of the fuel burn?

Accepted Answer

$$v = 117.6\ \mathrm{m/s}$$

Question 10

Which of the following best explains why a feather and a brick fall at the same rate in a vacuum?

Accepted Answer

There is no air resistance to impede the feather, so both objects experience only gravity.

Question 11

If the velocity of an object is positive and its acceleration is negative, what happens to the object's speed?

Accepted Answer

The object slows down.

Question 12

Which of the following is the correct expression for instantaneous acceleration?

Accepted Answer

$$a = \lim_{\Delta t 	o 0} \frac{\Delta v}{\Delta t}$$

Question 13

A car travels the first half of a trip at $$10\ \mathrm{km/h}$$ and the second half at $$90\ \mathrm{km/h}. $$What is the average speed for the entire trip?

Accepted Answer

$$v_{	ext{avg}} = 18\ \mathrm{km/h}$$

Question 14

Which of the following is NOT a scalar quantity?

Accepted Answer

Acceleration

Question 15

The area under a velocity vs. time graph represents which physical quantity?

Accepted Answer

Displacement

Question 16

Which of the following best describes the effect of air resistance on falling objects?

Accepted Answer

It slows down objects with large surface areas more than compact objects.

Question 17

A ball is thrown downward with an initial velocity of $$5.0\ \mathrm{m/s}$$ from a height of $$20.0\ \mathrm{m}. $$What is the equation for its position $$y as a $$function of time $$t ($$upward positive)?

Accepted Answer

$$y = 20.0 - 5.0 t - \frac{1}{2} (9.80) t^2$

Question 18

Which of the following is the correct kinematic equation to use when you do NOT know the time?

Accepted Answer

$$v^2$$ = $$v_0^2 + 2a$$\Delta x$$

Question 19

Which experiment provided strong evidence against Aristotle's claim that heavier objects fall faster than lighter ones?

Accepted Answer

Dropping a hammer and a feather on the Moon

Question 20

If an object moves with constant acceleration, which of the following statements is true?

Accepted Answer

The instantaneous acceleration is equal to the average acceleration.

Motion in One Dimension: Kinematics and Free Fall

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