Q: A ball is thrown vertically upward with an initial velocity of $15\ \mathrm{m/s}$. Ignoring air resistance, what is the maximum height reached by the ball? (Use $g = 9.8\ \mathrm{m/s^2}$)

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

Q: A car of mass $1000\ \mathrm{kg}$ traveling at $20\ \mathrm{m/s}$ collides with a stationary truck of mass $3000\ \mathrm{kg}$. If they stick together after the collision, what is their final velocity?

$v_f = \frac{m_1 v_1 + m_2 v_2}{m_1 + m_2} = \frac{1000 \times 20 + 3000 \times 0}{4000} = 5\ \mathrm{m/s}$

Q: A student lifts a $50\ \mathrm{kg}$ box to a height of $2\ \mathrm{m}$. How much work is done against gravity?

$W = mgh = 50 \times 9.8 \times 2 = 980\ \mathrm{J}$

Q: Two ice skaters push off from each other. Skater A has mass $60\ \mathrm{kg}$ and skater B has mass $40\ \mathrm{kg}$. If skater A moves at $3\ \mathrm{m/s}$, what is skater B's velocity?

$v_B = -\frac{m_A v_A}{m_B} = -\frac{60 \times 3}{40} = -4.5\ \mathrm{m/s}$

Q: A $5\ \mathrm{kg}$ object is dropped from a height of $10\ \mathrm{m}$. What is its velocity just before hitting the ground? (Ignore air resistance)

$v = \sqrt{2gh} = \sqrt{2 \times 9.8 \times 10} \approx 14\ \mathrm{m/s}$

Question 1

A car accelerates uniformly from rest along a straight line for 10 seconds, reaching a final velocity of 20 m/s. What is the car's acceleration?

Accepted Answer

$a = \frac{20}{10} = 2\ \mathrm{m/s^2}$

Question 2

A ball is thrown vertically upward with an initial velocity of $15\ \mathrm{m/s}$. Ignoring air resistance, what is the maximum height reached by the ball? (Use $g = 9.8\ \mathrm{m/s^2}$)

Accepted Answer

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

Question 3

A hockey puck slides across frictionless ice with a constant velocity. Which of Newton's Laws best explains why the puck continues moving?

Accepted Answer

Newton's First Law: An object in motion remains in motion unless acted upon by a net force.

Question 4

A 2 kg block is pushed with a force of 10 N on a frictionless surface. What is its acceleration?

Accepted Answer

$a = \frac{F}{m} = \frac{10}{2} = 5\ \mathrm{m/s^2}$

Question 5

A car of mass $1000\ \mathrm{kg}$ traveling at $20\ \mathrm{m/s}$ collides with a stationary truck of mass $3000\ \mathrm{kg}$. If they stick together after the collision, what is their final velocity?

Accepted Answer

$v_f = \frac{m_1 v_1 + m_2 v_2}{m_1 + m_2} = \frac{1000 	imes 20 + 3000 	imes 0}{4000} = 5\ \mathrm{m/s}$

Question 6

A satellite orbits Earth in a circular path. Which force provides the necessary centripetal acceleration?

Accepted Answer

Gravitational force: $F = G\frac{m_1 m_2}{r^2}$

Question 7

A student lifts a $50\ \mathrm{kg}$ box to a height of $2\ \mathrm{m}$. How much work is done against gravity?

Accepted Answer

$W = mgh = 50 	imes 9.8 	imes 2 = 980\ \mathrm{J}$

Question 8

A spinning disk has a moment of inertia $I$ and angular velocity $\omega$. What is its rotational kinetic energy?

Accepted Answer

$K = \frac{1}{2} I \omega^2$

Question 9

A block slides down a frictionless incline of height $h$. What is its speed at the bottom?

Accepted Answer

$v = \sqrt{2gh}$

Question 10

Two ice skaters push off from each other. Skater A has mass $60\ \mathrm{kg}$ and skater B has mass $40\ \mathrm{kg}$. If skater A moves at $3\ \mathrm{m/s}$, what is skater B's velocity?

Accepted Answer

$v_B = -\frac{m_A v_A}{m_B} = -\frac{60 	imes 3}{40} = -4.5\ \mathrm{m/s}$

Question 11

A pendulum swings with a period $T$. If its length is quadrupled, what happens to the period?

Accepted Answer

$T' = 2T$

Question 12

A car rounds a curve of radius $50\ \mathrm{m}$ at $10\ \mathrm{m/s}$. What is the required centripetal acceleration?

Accepted Answer

$a_c = \frac{v^2}{r} = \frac{10^2}{50} = 2\ \mathrm{m/s^2}$

Question 13

A $5\ \mathrm{kg}$ object is dropped from a height of $10\ \mathrm{m}$. What is its velocity just before hitting the ground? (Ignore air resistance)

Accepted Answer

$v = \sqrt{2gh} = \sqrt{2 	imes 9.8 	imes 10} \approx 14\ \mathrm{m/s}$

Question 14

A $0.2\ \mathrm{kg}$ ball moving at $5\ \mathrm{m/s}$ collides elastically with a stationary $0.3\ \mathrm{kg}$ ball. What is the velocity of the $0.2\ \mathrm{kg}$ ball after the collision?

Accepted Answer

$v_1' = \frac{m_1 - m_2}{m_1 + m_2} v_1 = \frac{0.2 - 0.3}{0.5} 	imes 5 = -1\ \mathrm{m/s}$

Question 15

A $10\ \mathrm{kg}$ object is moving at $4\ \mathrm{m/s}$. What is its kinetic energy?

Accepted Answer

$K = \frac{1}{2} m v^2 = \frac{1}{2} 	imes 10 	imes 16 = 80\ \mathrm{J}$

Question 16

A $2\ \mathrm{kg}$ mass attached to a $0.5\ \mathrm{m}$ string rotates in a horizontal circle at $3\ \mathrm{m/s}$. What is the tension in the string?

Accepted Answer

$T = \frac{m v^2}{r} = \frac{2 	imes 9}{0.5} = 36\ \mathrm{N}$

Question 17

A $1\ \mathrm{kg}$ object is dropped from rest and falls for $3\ \mathrm{s}$. What is its velocity just before hitting the ground? (Ignore air resistance)

Accepted Answer

$v = g t = 9.8 	imes 3 = 29.4\ \mathrm{m/s}$

Question 18

A $0.5\ \mathrm{kg}$ ball is thrown horizontally from a $20\ \mathrm{m}$ high cliff with a speed of $8\ \mathrm{m/s}$. How far from the base of the cliff does it land? (Ignore air resistance)

Accepted Answer

$t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{40}{9.8}} \approx 2.02\ \mathrm{s}$;\ d = v t = 8 	imes 2.02 \approx 16.2\ \mathrm{m}$

Physics 1050: Course Syllabus and Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards