Q: A car starts from rest and accelerates uniformly at $$2\ \mathrm{m/s^2$}$$ for $$5\ \mathrm{s}. $$What is its final velocity?

$$v = v_0$ + at = 0 + 2 \times 5 = 10\ \mathrm{m/s}$$

Q: A projectile is launched at an angle $$\theta$$ with initial speed $$v_0. $$Which equation gives the maximum height $$H$$ reached?

$$H = \frac{v_0$^2 \sin^2$ \theta}{2g}$$

Q: A $$5\ \mathrm{kg}$$ block and a $$3\ \mathrm{kg}$$ block are connected by a string and hang vertically. If the system is in equilibrium, what is the tension in the string?

$$T = m_1$ g = 5 \times 9.8 = 49.0\ \mathrm{N}$$

Question 1

A vector $$	extbf{A}$$ has components $$A_x = 3$$ and $$A_y = 4. $$What is the magnitude of $$	extbf{A}$$?

Accepted Answer

$$\sqrt{3^2$ + 4^2$} = 5$$

Question 2

A car starts from rest and accelerates uniformly at $$2\ \mathrm{m/s^2$}$$ for $$5\ \mathrm{s}. $$What is its final velocity?

Accepted Answer

$$v = v_0$ + at = 0 + 2 	imes 5 = 10\ \mathrm{m/s}$$

Question 3

A ball is dropped from a height of $$20\ \mathrm{m}. $$Neglecting air resistance, how long does it take to reach the ground? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{40}{9.8}} \approx 2.02\ \mathrm{s}$$

Question 4

Which of the following best describes the velocity-time graph for an object in free fall (neglecting air resistance)?

Accepted Answer

A straight line with positive slope

Question 5

A projectile is launched at an angle $$	heta$$ with initial speed $$v_0. $$Which equation gives the maximum height $$H$$ reached?

Accepted Answer

$$H = \frac{v_0$^2 \sin^2$ 	heta}{2g}$$

Question 6

A soccer ball is kicked horizontally from a $$2\ \mathrm{m}$$ high table with a speed of $$5\ \mathrm{m/s}. $$How far does it travel horizontally before hitting the ground? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{4}{9.8}} \approx 0.64\ \mathrm{s}$$; \quad x = $$v_0 t = 5$$ 	imes 0.64 = 3.2\ \mathrm{m}$

Question 7

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

Accepted Answer

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

Question 8

Which statement about uniform circular motion is correct?

Accepted Answer

The speed is constant, but the velocity changes direction continuously.

Question 9

An elevator is accelerating upward with acceleration $$a. $$What is the apparent weight $$W' of a $$person of mass $$m$$ inside the elevator?

Accepted Answer

$$W' = m(g + a)$$

Question 10

Two blocks, $$m_1 = 2$$\ \mathrm{kg}$$ and m_2$ = 3\ \mathrm{kg}$$, are connected by a string and pulled by a force $$F = 20\ \mathrm{N} on a $$frictionless surface. What is the acceleration of the system?

Accepted Answer

$$a = \frac{F}{m_1$ + m_2$} = \frac{20}{5} = 4\ \mathrm{m/s^2$}$$

Question 11

A $$5\ \mathrm{kg}$$ block and a $$3\ \mathrm{kg}$$ block are connected by a string and hang vertically. If the system is in equilibrium, what is the tension in the string?

Accepted Answer

$$T = m_1$ g = 5 	imes 9.8 = 49.0\ \mathrm{N}$$

Question 12

A $$10\ \mathrm{kg}$$ box is pushed with a force of $$30\ \mathrm{N} on a $$frictionless surface. What is its acceleration?

Accepted Answer

$$a = \frac{F}{m} = \frac{30}{10} = 3\ \mathrm{m/s^2$}$$

Question 13

A $$4\ \mathrm{kg}$$ block slides down a frictionless incline of $$30^\circ. $$What is its acceleration?

Accepted Answer

$$a = g \sin 	heta = 9.8 \sin 30^\circ = 4.9\ \mathrm{m/s^2$}$$

Question 14

A $$5\ \mathrm{kg}$$ block slides down a $$30^\circ$$ incline with a coefficient of kinetic friction $$\mu_k = 0.2. $$What is the net acceleration?

Accepted Answer

$$a = g \sin 	heta - \mu_k g \cos 	heta = 9.8 \sin 30^\circ - 0.2 	imes 9.8 \cos 30^\circ \approx 4.9 - 1.7 = 3.2\ \mathrm{m/s^2$}$$

Question 15

Which statement about static and kinetic friction is correct?

Accepted Answer

Static friction can be greater than kinetic friction for the same surfaces.

Question 16

A $$10\ \mathrm{kg}$$ box rests on a horizontal surface. The coefficient of static friction is $$0.5. $$What is the minimum force required to start moving the box?

Accepted Answer

$$F_{	ext{min}} = \mu_s N = 0.5 	imes 10 	imes 9.8 = 49\ \mathrm{N}$$

PHY2048 Exam 1 Study Guide: Chapters 1–5 (Vectors, Kinematics, Newton’s Laws, and Applications)

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