Q: A car travels 60 km north, then 80 km east. What is the magnitude of its displacement from the starting point?

$$\sqrt{60^2$ + 80^2$} = 100\ \text{km}$$

Q: A ball is thrown vertically upward with an initial velocity of $$20\ \text{m/s}. $$Neglecting air resistance, what is the maximum height it reaches? (Take $$g = 9.8\ \text{m/s}^2)$$

$$\frac{(20)^2$}{2 \times 9.8} = 20.4\ \text{m}$$

Q: A projectile is launched at an angle $$\theta$$ above the horizontal with initial speed $$v_0. $$Which of the following gives the time of flight until it returns to the same vertical level?

$$\frac{2 v_0$ \sin \theta}{g}$$

Q: A 5 kg block is pulled across a horizontal surface with a constant force of 20 N. If the coefficient of kinetic friction is 0.2, what is the acceleration of the block? (Take $$g = 9.8\ \text{m/s}^2)$$

$$\frac{20 - (0.2 \times 5 \times 9.8)}{5} = 2.08\ \text{m/s}^2$$

Q: A 0.5 kg ball is dropped from a height of 10 m. What is its speed just before hitting the ground? (Neglect air resistance, $$g = 9.8\ \text{m/s}^2)$$

$$\sqrt{2 \times 9.8 \times 10} = 14\ \text{m/s}$$

Q: A 3 kg mass is attached to a spring with spring constant $$k = 150\ \text{N/m}. $$What is the period of oscillation?

$$2\pi \sqrt{\frac{3}{150}} = 0.89\ \text{s}$$

Q: A cyclist increases her speed from $$5\ \text{m/s} to$$ $$15\ \text{m/s} in 5 $$seconds. What is her average acceleration?

$$\frac{15 - 5}{5} = 2\ \text{m/s}^2$$

Q: A 10 kg box is at rest on a rough horizontal floor. The coefficient of static friction is 0.4. What is the minimum force required to start moving the box? (Take $$g = 9.8\ \text{m/s}^2)$$

$$0.4 \times 10 \times 9.8 = 39.2\ \text{N}$$

Q: A 2 kg object moves in a circle of radius 0.5 m at a constant speed of $$4\ \text{m/s}. $$What is the magnitude of the centripetal force acting on it?

$$\frac{2 \times 4^2$}{0.5} = 64\ \text{N}$$

Q: A 1.5 kg block slides down a frictionless incline of height 3 m. What is its speed at the bottom?

$$\sqrt{2 \times 9.8 \times 3} = 7.67\ \text{m/s}$$

Question 1

A car travels 60 km north, then 80 km east. What is the magnitude of its displacement from the starting point?

Accepted Answer

$$\sqrt{60^2$ + 80^2$} = 100\ 	ext{km}$$

Question 2

A ball is thrown vertically upward with an initial velocity of $$20\ 	ext{m/s}. $$Neglecting air resistance, what is the maximum height it reaches? (Take $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$\frac{(20)^2$}{2 	imes 9.8} = 20.4\ 	ext{m}$$

Question 3

A projectile is launched at an angle $$	heta$$ above the horizontal with initial speed $$v_0. $$Which of the following gives the time of flight until it returns to the same vertical level?

Accepted Answer

$$\frac{2 v_0$ \sin 	heta}{g}$$

Question 4

A 5 kg block is pulled across a horizontal surface with a constant force of 20 N. If the coefficient of kinetic friction is 0.2, what is the acceleration of the block? (Take $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$\frac{20 - (0.2 	imes 5 	imes 9.8)}{5} = 2.08\ 	ext{m/s}^2$$

Question 5

A 2 kg object moving at $$3\ 	ext{m/s}$$ collides elastically with a stationary 1 kg object. What is the velocity of the 2 kg object after the collision?

Accepted Answer

Question 6

A 0.5 kg ball is dropped from a height of 10 m. What is its speed just before hitting the ground? (Neglect air resistance, $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$\sqrt{2 	imes 9.8 	imes 10} = 14\ 	ext{m/s}$$

Question 7

A 3 kg mass is attached to a spring with spring constant $$k = 150\ 	ext{N/m}. $$What is the period of oscillation?

Accepted Answer

$$2\pi \sqrt{\frac{3}{150}} = 0.89\ 	ext{s}$$

Question 8

A cyclist increases her speed from $$5\ 	ext{m/s} to$$ $$15\ 	ext{m/s} in 5 $$seconds. What is her average acceleration?

Accepted Answer

$$\frac{15 - 5}{5} = 2\ 	ext{m/s}^2$$

Question 9

A 10 kg box is at rest on a rough horizontal floor. The coefficient of static friction is 0.4. What is the minimum force required to start moving the box? (Take $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$0.4 	imes 10 	imes 9.8 = 39.2\ 	ext{N}$$

Question 10

A 2 kg object moves in a circle of radius 0.5 m at a constant speed of $$4\ 	ext{m/s}. $$What is the magnitude of the centripetal force acting on it?

Accepted Answer

$$\frac{2 	imes 4^2$}{0.5} = 64\ 	ext{N}$$

Question 11

A 1.5 kg block slides down a frictionless incline of height 3 m. What is its speed at the bottom?

Accepted Answer

$$\sqrt{2 	imes 9.8 	imes 3} = 7.67\ 	ext{m/s}$$

Question 12

A 0.2 kg ball moving at $$10\ 	ext{m/s}$$ strikes a wall and rebounds with a speed of $$8\ 	ext{m/s} in $$the opposite direction. What is the magnitude of the change in momentum?

Accepted Answer

$$0.2 	imes (10 + 8) = 3.6\ 	ext{kg} \cdot 	ext{m/s}$$

Question 13

A 1000 kg car moving at $$20\ 	ext{m/s}$$ comes to a stop in 5 seconds. What is the average force exerted by the brakes?

Accepted Answer

$$\frac{1000 	imes (0 - 20)}{5} = -4000\ 	ext{N}$$

Question 14

A 0.5 kg mass is attached to a string and swung in a horizontal circle of radius 2 m at a speed of $$6\ 	ext{m/s}. $$What is the tension in the string?

Accepted Answer

$$\frac{0.5 	imes 6^2$}{2} = 9\ 	ext{N}$$

Question 15

A 2 kg object is moving at $$5\ 	ext{m/s} to $$the right. A constant force of $$-4\ 	ext{N}$$ acts on it for 3 seconds. What is its final velocity?

Accepted Answer

Question 16

A 0.1 kg bullet is fired horizontally at $$400\ 	ext{m/s}$$ into a 2 kg block at rest on a frictionless surface. The bullet embeds in the block. What is their final speed?

Accepted Answer

$$\frac{0.1 	imes 400}{0.1 + 2} = 19.05\ 	ext{m/s}$$

Question 17

A 5 kg object is moving at $$2\ 	ext{m/s}. $$What is its kinetic energy?

Accepted Answer

$$\frac{1}{2} 	imes 5 	imes 2^2$ = 10\ 	ext{J}$$

Question 18

A 60 kg astronaut pushes off a 180 kg satellite in space. If the astronaut moves away at $$3\ 	ext{m/s}$$, what is the velocity of the satellite?

Accepted Answer

$$\frac{60 	imes 3}{180} = 1\ 	ext{m/s} ($$opposite direction)

Question 19

A 2 kg block is attached to a horizontal spring and oscillates with amplitude 0.1 m and period 0.5 s. What is the maximum speed of the block?

Accepted Answer

$$v_{max} = \omega A = \frac{2\pi}{0.5} 	imes 0.1 = 1.26\ 	ext{m/s}$$

Question 20

A 1 kg object is moving in a circle of radius 2 m at a constant speed of $$3\ 	ext{m/s}. $$What is its angular momentum about the center?

Accepted Answer

$$L = m v r = 1 	imes 3 	imes 2 = 6\ 	ext{kg} \cdot 	ext{m}^2/	ext{s}$$

Physics Exam 1 Study Guidance: Chapters 1–3 Problem List

Study Guide - Practice Questions

Study Guide - Flashcards