Q: A car travels 120 km in 2 hours. What is its average speed, and how does this differ from its average velocity if the car returns to its starting point?

Average speed is $$60\ \text{km/h}$$; average velocity is $$0\ \text{km/h}$$ because displacement is zero.

Q: A projectile is launched from ground level with an initial velocity of $$v_0 = 20$$\ \text{m/s}$$ at an angle of 30$$^\circ$$ above the horizontal. What is the horizontal component of its initial velocity?

$$v_{0x} = 20 \cos 30^\circ = 17.3\ \text{m/s}$$

Q: A ball is thrown vertically upward with an initial velocity of $$15\ \text{m/s}. $$Using the kinematic equations, how long does it take to reach its maximum height?

$$t = \frac{v_0$}{g} = \frac{15}{9.8} = 1.53\ \text{s}$$

Q: Which of the following is NOT a correct application of dimensional analysis?

Adding a mass ($$\text{kg}) to a $$length ($$\text{m}).$$

Q: A cyclist accelerates from rest at $$2\ \text{m/s}^2$$ for $$5\ \text{s}. $$What is the final velocity using the kinematic equation $$v = v_0$ + at$$?

$$v = 0 + 2 \times 5 = 10\ \text{m/s}$$

Q: A stone is dropped from a cliff and hits the ground after $$4\ \text{s}. $$What is the height of the cliff? (Assume $$g = 9.8\ \text{m/s}^2$$ and use $$y = v_0$ t + \frac{1}{2} a t^2$)

$$y = 0 + \frac{1}{2} \times 9.8 \times 4^2$ = 78.4\ \text{m}$$

Question 1

A car travels 120 km in 2 hours. What is its average speed, and how does this differ from its average velocity if the car returns to its starting point?

Accepted Answer

Average speed is $$60\ 	ext{km/h}$$; average velocity is $$0\ 	ext{km/h}$$ because displacement is zero.

Question 2

Which of the following best describes the difference between displacement and distance traveled?

Accepted Answer

Displacement is the straight-line change in position, while distance is the total length of the path traveled.

Question 3

A projectile is launched from ground level with an initial velocity of $$v_0 = 20$$\ 	ext{m/s}$$ at an angle of 30$$^\circ$$ above the horizontal. What is the horizontal component of its initial velocity?

Accepted Answer

$$v_{0x} = 20 \cos 30^\circ = 17.3\ 	ext{m/s}$$

Question 4

Which of the following statements about free fall is correct?

Accepted Answer

In free fall, the only force acting on the object is gravity, and acceleration is $$g = 9.8\ 	ext{m/s}^2$$ downward.

Question 5

A vector $$	extbf{A}$$ has a magnitude of $$5$$ and points $$53^\circ$$ above the x-axis. What are its x and y components?

Accepted Answer

$$A_x = 5 \cos 53^\circ = 3.0$$, $$A_y = 5 \sin 53^\circ = 4.0$$

Question 6

A ball is thrown vertically upward with an initial velocity of $$15\ 	ext{m/s}. $$Using the kinematic equations, how long does it take to reach its maximum height?

Accepted Answer

$$t = \frac{v_0$}{g} = \frac{15}{9.8} = 1.53\ 	ext{s}$$

Question 7

Which of the following is NOT a correct application of dimensional analysis?

Accepted Answer

Adding a mass ($$	ext{kg}) to a $$length ($$	ext{m}).$$

Question 8

A vector $$	extbf{B} is $$given in unit vector form as $$	extbf{B} = 2\hat{i} + 3\hat{j}. $$What is its magnitude and direction relative to the x-axis?

Accepted Answer

Magnitude: $$\sqrt{2^2$ + 3^2$} = \sqrt{13} = 3.6$$; Direction: $$	an$$^{-1}$$(\frac{3}{2}) = 56.3^\circ$$

Question 9

A cyclist accelerates from rest at $$2\ 	ext{m/s}^2$$ for $$5\ 	ext{s}. $$What is the final velocity using the kinematic equation $$v = v_0$ + at$$?

Accepted Answer

$$v = 0 + 2 	imes 5 = 10\ 	ext{m/s}$$

Question 10

A stone is dropped from a cliff and hits the ground after $$4\ 	ext{s}. $$What is the height of the cliff? (Assume $$g = 9.8\ 	ext{m/s}^2$$ and use $$y = v_0$ t + \frac{1}{2} a t^2$)

Accepted Answer

$$y = 0 + \frac{1}{2} 	imes 9.8 	imes 4^2$ = 78.4\ 	ext{m}$$

Question 11

Which statement about projectile motion on planet Earth is always true?

Accepted Answer

The horizontal acceleration is zero, and the vertical acceleration is $$-g.$$

Question 12

A car moves in a circle of radius $$10\ 	ext{m} at a $$constant speed of $$5\ 	ext{m/s}. $$What is the magnitude of its centripetal acceleration?

Accepted Answer

$$a_c = \frac{v^2$}{r} = \frac{25}{10} = 2.5\ 	ext{m/s}^2$$

Question 13

Which of the following best describes the direction of centripetal acceleration in uniform circular motion?

Accepted Answer

It always points toward the center of the circle.

Question 14

A runner moves along the x-axis from $$x = 0 to$$ $$x = 50\ 	ext{m} in$$ $$10\ 	ext{s}$$, then returns to $$x = 0 in $$another $$10\ 	ext{s}. $$What is the average velocity for the entire trip?

Accepted Answer

Average velocity is $$0\ 	ext{m/s}$$ because total displacement is zero.

Question 15

A particle moves in a circle of radius $$r$$ with angular speed $$\omega. $$What is the period $$T of $$its motion?

Accepted Answer

$$T = \frac{2\pi}{\omega}$$

Question 16

Which of the following is a correct statement about significant figures in physics calculations?

Accepted Answer

The number of significant figures in the result should not exceed that of the least precise measurement used.

Question 17

A car accelerates from $$10\ 	ext{m/s} to$$ $$30\ 	ext{m/s} in$$ $$5\ 	ext{s}. $$What is its average acceleration?

Accepted Answer

$$a_{avg} = \frac{30 - 10}{5} = 4\ 	ext{m/s}^2$$

Question 18

A projectile is launched horizontally from a $$45\ 	ext{m}$$ high cliff. How long does it take to hit the ground? (Use $$y = \frac{1}{2} g t^2$)

Accepted Answer

$$t = \sqrt{\frac{2y}{g}} = \sqrt{\frac{90}{9.8}} = 3.03\ 	ext{s}$$

Question 19

Which of the following best describes radial and tangential acceleration in circular motion?

Accepted Answer

Radial acceleration points toward the center and is responsible for changing direction; tangential acceleration changes the speed.

PHYS 180 Study Guide: Chapters 1–4 (Units, Kinematics, Vectors, and Circular Motion)

Study Guide - Practice Questions

Study Guide - Flashcards