Q: A rock is thrown straight down from a window $$65\ \mathrm{m}$$ above the ground with an initial velocity of $$14\ \mathrm{m/s}. $$What is the velocity of the rock just before it hits the ground? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

$$v = \sqrt{14^2$ + 2 \times 9.8 \times 65}$$

Question 1

A car moves along a straight road as shown in the first motion diagram (first image). Which of the following best describes the car's velocity and acceleration?

Accepted Answer

The car has a constant negative velocity and zero acceleration.

Question 2

In the second motion diagram (second image), what is the direction of the car's velocity and what does this indicate about its motion?

Accepted Answer

The car is moving to the right with constant speed.

Question 3

Refer to the velocity-time graph (third image). What is the acceleration of the object between $$t = 5\ \mathrm{s}$$ and $$t = 10\ \mathrm{s}$$?

Accepted Answer

$$a = 0\ \mathrm{m/s^2$}$$

Question 4

In the triple graph (fourth image), what does the area under the velocity-time curve represent?

Accepted Answer

The object's displacement.

Question 5

In the secant and tangent line diagram (fifth image), what does the slope of the tangent line represent in a position-time graph?

Accepted Answer

The object's instantaneous velocity at a point.

Question 6

Which velocity-time graph (sixth image) represents an object moving with constant negative acceleration?

Accepted Answer

Fig 4.4 (g)

Question 7

Given the velocity-time graph (seventh image), what is the total displacement of the object from $$t = 0 to$$ $$t = 20\ \mathrm{s}$$?

Accepted Answer

The sum of the areas under the curve, counting areas below the axis as negative.

Question 8

You toss a ball up into the air. At its peak, the ball’s velocity and acceleration are (see eighth image):

Accepted Answer

Velocity is zero, but its acceleration is nonzero.

Question 9

An arrow is launched vertically upward (ninth image). Which of the following best describes the acceleration of the arrow during its flight (ignoring air resistance)?

Accepted Answer

The acceleration is always downward and constant.

Question 10

A car starts from rest and accelerates at $$4.0\ \mathrm{m/s^2$}$$ for $$6.0\ \mathrm{s}$$, then coasts for $$2.0\ \mathrm{s}$$, and finally slows down at $$3.0\ \mathrm{m/s^2$}$$ until it stops. What is the total distance traveled by the car?

Accepted Answer

$$172\ \mathrm{m}$$

Question 11

A rock is thrown straight down from a window $$65\ \mathrm{m}$$ above the ground with an initial velocity of $$14\ \mathrm{m/s}. $$What is the velocity of the rock just before it hits the ground? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$v = \sqrt{14^2$ + 2 	imes 9.8 	imes 65}$$

Question 12

Suppose you travel at a constant $$40\ \mathrm{km/h}$$ and see a deer $$13\ \mathrm{m}$$ ahead. Your reaction time is $$0.25\ \mathrm{s}$$, and you decelerate at $$8.0\ \mathrm{m/s^2$}. Do $$you hit the deer?

Accepted Answer

No, you stop $$7\ \mathrm{m}$$ away from the deer.

Question 13

Which kinematic equation would you use to find the time it takes for an object to reach the ground when dropped from a height $$h$$ with initial velocity $$v_i$$?

Accepted Answer

$$x_f = x_i + v_i t + \frac{1}{2} a t^2$

Question 14

If the velocity-time graph of an object is a straight line with a positive slope, what can you say about the object's acceleration?

Accepted Answer

The object has constant positive acceleration.

Question 15

For an object moving with constant acceleration, which of the following is always true?

Accepted Answer

The velocity-time graph is a straight line.

Question 16

A ball is thrown upward with an initial velocity of $$5.0\ \mathrm{m/s}$$ from a height of $$1.0\ \mathrm{m}. $$What is the maximum height reached by the ball? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$h_{max} = 1.0 + \frac{(5.0)^2$}{2 	imes 9.8}$$

Question 17

If the area under a velocity-time graph is negative, what does this indicate about the object's displacement?

Accepted Answer

The object has moved in the negative direction.

Question 18

Which of the following statements about freely falling objects is correct?

Accepted Answer

All objects fall with the same constant acceleration regardless of mass.

Motion Graphs and Kinematics: Study Notes for College Physics

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