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

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 \times 20}{9.8}} \approx 2.02\ \mathrm{s}$$

Q: A projectile is launched at an angle $$\theta$$ with initial speed $$v_0. $$What is the formula for its maximum height?

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

Q: A runner accelerates from rest at $$2\ \mathrm{m/s^2$}$$ for 5 seconds. What is the runner's final velocity?

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

Q: A ball is thrown horizontally from a cliff with a speed of $$10\ \mathrm{m/s}. If $$the cliff is $$45\ \mathrm{m}$$ high, how far from the base of the cliff does the ball land? ($$g = 9.8\ \mathrm{m/s^2$})$$

Horizontal distance $$= v_x t = 10 \times \sqrt{\frac{2 \times 45}{9.8}} \approx 30.3\ \mathrm{m}$$

Question 1

A car travels 100 m east, then 50 m west. What is the car's displacement and total distance traveled?

Accepted Answer

Displacement: 50 m east; Total distance: 150 m

Question 2

Which of the following best describes the difference between speed and velocity?

Accepted Answer

Speed is a scalar quantity; velocity is a vector quantity.

Question 3

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

Accepted Answer

$$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 	imes 20}{9.8}} \approx 2.02\ \mathrm{s}$$

Question 4

Which kinematic equation would you use to find the final velocity of an object given its initial velocity, acceleration, and displacement?

Accepted Answer

$$v^2$$ = $$v_0^2 + 2a$$\Delta x$$

Question 5

A projectile is launched at an angle $$	heta$$ with initial speed $$v_0. $$What is the formula for its maximum height?

Accepted Answer

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

Question 6

Which of the following is true about acceleration?

Accepted Answer

Acceleration is the rate of change of velocity.

Question 7

A runner accelerates from rest at $$2\ \mathrm{m/s^2$}$$ for 5 seconds. What is the runner's final velocity?

Accepted Answer

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

Question 8

Which statement about Newton's First Law is correct?

Accepted Answer

An object at rest remains at rest unless acted upon by a net external force.

Question 9

A box is pulled across a horizontal surface with a force of 20 N. The coefficient of kinetic friction is 0.4 and the box has a mass of 5 kg. What is the acceleration of the box? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$a = \frac{F_{applied} - F_{friction}}{m} = \frac{20 - (0.4 	imes 5 	imes 9.8)}{5} = \frac{20 - 19.6}{5} = 0.08\ \mathrm{m/s^2$}$$

Question 10

Which of the following is NOT a type of force discussed in Chapters 4 & 5?

Accepted Answer

Magnetic force

Question 11

A ball is thrown horizontally from a cliff with a speed of $$10\ \mathrm{m/s}. If $$the cliff is $$45\ \mathrm{m}$$ high, how far from the base of the cliff does the ball land? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

Horizontal distance $$= v_x t = 10 	imes \sqrt{\frac{2 	imes 45}{9.8}} \approx 30.3\ \mathrm{m}$$

Question 12

Which of the following best describes inertia?

Accepted Answer

The tendency of an object to resist changes in its motion.

Question 13

A person pushes a 10 kg box with a force of 50 N horizontally. The coefficient of static friction is 0.6. Will the box move? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

No, because $$F_{static,max} = \mu_s N = 0.6 	imes 10 	imes 9.8 = 58.8\ \mathrm{N}$$, which is greater than 50 N.

Question 14

Which of the following is a correct statement about the relationship between weight and mass?

Accepted Answer

Weight is the force due to gravity acting on mass: $$W = mg$$

Question 15

A soccer ball is kicked at $$20\ \mathrm{m/s} at an $$angle of $$30^\circ$$ above the horizontal. What is the time of flight? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$t = \frac{2 v_0$ \sin 	heta}{g} = \frac{2 	imes 20 	imes \sin 30^\circ}{9.8} = \frac{20}{9.8} \approx 2.04\ \mathrm{s}$$

Question 16

Which of the following is true about friction forces?

Accepted Answer

Kinetic friction acts when objects are sliding; static friction acts when objects are not moving relative to each other.

Question 17

A 2 kg object is moving at a constant velocity on a horizontal surface. What can you conclude about the net force acting on the object?

Accepted Answer

The net force is zero.

Question 18

Which of the following is an example of a restoring force?

Accepted Answer

Spring force

Question 19

Which factor does NOT influence drag force on an object moving through air?

Accepted Answer

The color of the object

Exam 1 Physics Study Guide: Kinematics, Vectors, and Forces

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