Q: A ball is thrown vertically upward with an initial velocity of $$v_0 = 15$$\ \mathrm{m/s}$$. Neglecting air resistance, what is the maximum height reached by the ball?

$$h = \frac{v_0$^2}{2g} = \frac{15^2$}{2 \times 9.8} \approx 11.5\ \mathrm{m}$$

Q: A 2 kg block slides down a frictionless incline of height 5 m. What is its speed at the bottom?

$$v = \sqrt{2gh} = \sqrt{2 \times 9.8 \times 5} \approx 9.9\ \mathrm{m/s}$$

Q: A projectile is launched at an angle $$\theta$$ with initial speed $$v_0. $$What is the formula for its maximum range (assuming level ground and neglecting air resistance)?

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

Q: A 10 kg box is pulled across a horizontal surface with a force of 50 N. If the coefficient of kinetic friction is $$\mu_k = 0.2$$, what is the acceleration of the box?

$$a = \frac{F - \mu_k mg}{m} = \frac{50 - 0.2 \times 10 \times 9.8}{10} = \frac{50 - 19.6}{10} = 3.04\ \mathrm{m/s^2$}$$

Q: A student drops a ball from a height of 2 m. How long does it take to hit the ground? (Neglect air resistance)

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 \times 2}{9.8}} \approx 0.64\ \mathrm{s}$$

Q: A cyclist increases her speed from 5 m/s to 15 m/s over a distance of 100 m. What is her acceleration, assuming it is constant?

$$a = \frac{v^2$ - v_0$^2}{2d} = \frac{15^2$ - 5^2$}{2 \times 100} = \frac{225 - 25}{200} = 1\ \mathrm{m/s^2$}$$

Question 1

A car accelerates uniformly from rest to a speed of 20 m/s in 5 seconds. What is the magnitude of its acceleration?

Accepted Answer

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

Question 2

Which of the following best describes Newton's First Law of Motion?

Accepted Answer

An object in motion remains in motion unless acted upon by an external force.

Question 3

A ball is thrown vertically upward with an initial velocity of $$v_0 = 15$$\ \mathrm{m/s}$$. Neglecting air resistance, what is the maximum height reached by the ball?

Accepted Answer

$$h = \frac{v_0$^2}{2g} = \frac{15^2$}{2 	imes 9.8} \approx 11.5\ \mathrm{m}$$

Question 4

A 2 kg block slides down a frictionless incline of height 5 m. What is its speed at the bottom?

Accepted Answer

$$v = \sqrt{2gh} = \sqrt{2 	imes 9.8 	imes 5} \approx 9.9\ \mathrm{m/s}$$

Question 5

Which of the following is a vector quantity?

Accepted Answer

Displacement

Question 6

A projectile is launched at an angle $$	heta$$ with initial speed $$v_0. $$What is the formula for its maximum range (assuming level ground and neglecting air resistance)?

Accepted Answer

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

Question 7

A 10 kg box is pulled across a horizontal surface with a force of 50 N. If the coefficient of kinetic friction is $$\mu_k = 0.2$$, what is the acceleration of the box?

Accepted Answer

$$a = \frac{F - \mu_k mg}{m} = \frac{50 - 0.2 	imes 10 	imes 9.8}{10} = \frac{50 - 19.6}{10} = 3.04\ \mathrm{m/s^2$}$$

Question 8

Which statement best describes the conservation of momentum in a collision?

Accepted Answer

The total momentum of a closed system remains constant if no external forces act on it.

Question 9

A student drops a ball from a height of 2 m. How long does it take to hit the ground? (Neglect air resistance)

Accepted Answer

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 	imes 2}{9.8}} \approx 0.64\ \mathrm{s}$$

Question 10

Which of the following is NOT a fundamental SI unit?

Accepted Answer

Newton

Question 11

A cyclist increases her speed from 5 m/s to 15 m/s over a distance of 100 m. What is her acceleration, assuming it is constant?

Accepted Answer

$$a = \frac{v^2$ - v_0$^2}{2d} = \frac{15^2$ - 5^2$}{2 	imes 100} = \frac{225 - 25}{200} = 1\ \mathrm{m/s^2$}$$

Question 12

Which of the following best explains why astronauts feel 'weightless' while orbiting Earth?

Accepted Answer

They are in continuous free fall around Earth, experiencing no normal force.

Question 13

A 0.5 kg ball moving at 4 m/s collides head-on elastically with a stationary 0.5 kg ball. What is the velocity of the first ball after the collision?

Accepted Answer

$$v_1$$' = 0\ \mathrm{m/s}$$

Question 14

Which equation represents Newton's Second Law?

Accepted Answer

$$\vec{F} = m \vec{a}$$

Question 15

A 3 kg object is moving in a circle of radius 2 m at a speed of 6 m/s. What is the magnitude of the centripetal force acting on it?

Accepted Answer

$$F_c = \frac{mv^2$}{r} = \frac{3 	imes 6^2$}{2} = \frac{3 	imes 36}{2} = 54\ \mathrm{N}$$

Question 16

Which of the following is an example of a non-conservative force?

Accepted Answer

Friction

Question 17

A 5 kg object is lifted vertically by 3 m. How much work is done against gravity?

Accepted Answer

$$W = mgh = 5 	imes 9.8 	imes 3 = 147\ \mathrm{J}$$

Question 18

A car of mass 1000 kg moving at 20 m/s comes to a stop in 5 seconds. What is the average force exerted by the brakes?

Accepted Answer

$$F = m \frac{\Delta v}{\Delta t} = 1000 	imes \frac{0 - 20}{5} = -4000\ \mathrm{N}$$

Question 19

Which principle is used to analyze the equilibrium of a seesaw with two children of different masses sitting at different distances from the pivot?

Accepted Answer

The principle of moments (torque)

Study Guide: PHY 220 General Physics I (Grand Valley State University)

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