Call Now to Set Up Tutoring:

(888) 888-0446

AP Physics C: Mechanics : Friction and Normal Force

Study concepts, example questions & explanations for AP Physics C: Mechanics

Create An Account

All AP Physics C: Mechanics Resources

2 Diagnostic Tests 92 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #2 : Friction

A truck driver is making a delivery. He takes a 287kg box out of his semi-truck by having it slide down a 33^o ramp that is 5.5m long. To ensure that the box doesn't accelerate down the ramp, the driver pushes back on it so that the box's constant speed is $1.7\frac{m}{s}$ . If the coefficient of friction is 0.4, calculate the work done by the frictional force.

Possible Answers:

1049 J

6548 J

9675 J

5189 J

3987 J

Correct answer:

5189 J

Explanation:

We can calculate the work done by friction by using $W=F_{friction}\cdot d$ .

It is just the product of the friction force and the length of the ramp. Rewrite work as $W=\mu_kF_Nd$ .

Since this problem involves a box sliding down an incline, the normal force is $F_N=mg\cos\theta$ .

Work is now written as the equation below.

$W=\mu_kmg(\cos\theta) d$

We know the following information from the question.

$\mu_k=0.4$

m=287kg

$g=9.8\frac{m}{s^2}$

$\theta=33^{o}$

d=5.5m

using these values, we can calculate work from our equation.

$W=(0.4)(287kg)(9.8\frac{m}{s^2})(\cos(33))(5.5)$

W=5189 J

Report an Error

Example Question #2 : Friction

A string connected to a box sitting on the floor is used to apply a
force on the box as shown. The string is inclined at an angle of 30°
above the horizontal, the box has a mass of 15 kg, and the tension
in the string is 40 N. The box is at rest, but on the verge of slipping.
What is the coefficient of static friction between the box and the
floor?

Possible Answers:

0.273

0.154

0.479

0.212

0.338

Correct answer:

0.273

Explanation:

First, we know that the tension on the string is $40\:N$ at an angle of degrees from the horizontal. We must find the x and y components of the tension force.

$T_y = T\sin(30) = 40\cdot\sin(30)= 20\:N$

$T_x = T\cos(30) = 40\cos(30)= 34.64\:N$

Next, we must find the normal force acting on the block. The normal force of the block itself is $15\:kg \cdot 9.8\:m/s^2 = 147\:N$ , but there is a string pulling on it. We must subtract the y component of tension to get the final normal force

F_n = 147-20 = 127

Next, we know that the block is being pulled to the right, and the frictional force is acting in the opposite direction. So we get the equation:

$T_x - F_f = 0, F_f = \mu F_n$

$34.64 - \mu 127 = 0$

$\mu = 0.273$

Report an Error

Example Question #3 : Friction

$\begin{align*}&\text{A block of mass }51kg\text{ rests on an incline of }11^{\circ}\\&\text{What is the frictional force acting on the block from the surface?}\\&g=9.81\frac{m}{s^2}\end{align*}$

Possible Answers:

500.31N

50.06N

95.46N

491.12N

Correct answer:

95.46N

Explanation:

Normal

Report an Error

Example Question #4 : Friction

$\begin{align*}&\text{A block of mass }100kg\text{ rests on an incline of }73^{\circ}\\&\text{What is the frictional force acting on the block from the surface?}\\&g=9.81\frac{m}{s^2}\end{align*}$

Possible Answers:

29.24N

981N

938.13N

286.82N

Correct answer:

938.13N

Explanation:

Normal $\begin{align*}&\text{To solve a problem of force balance, a good idea is to draw}\\&\text{it out. Since the block is at rest, i.e. stationary, the sum}\\&\text{of forces acting on it must be equal to zero. The forces acting}\\&\text{on it are gravity (in the form of the mass times the gravitational}\\&\text{constant), a normal force, and since it’s on an incline, a frictional}\\&\text{force to balance it all out:}\\&F_{mass}=m*g\\&F_{normal}=m*g*cos(a)\\&F_{friction}=m*g*sin(a)\\&F_{friction}=100kg(9.81\frac{m}{s^2})(sin(73^{\circ}))\\&F_{friction}=938.13N\end{align*}$

Report an Error

Example Question #5 : Friction

$\begin{align*}&\text{A block of mass }19kg\text{ rests on an incline of }69^{\circ}\\&\text{What is the frictional force acting on the block from the surface?}\\&g=9.81\frac{m}{s^2}\end{align*}$

Possible Answers:

186.39N

174.01N

66.8N

6.81N

Correct answer:

174.01N

Explanation:

Normal

Report an Error

Example Question #4 : Friction

$\begin{align*}&\text{A block of mass }284kg\text{ rests on an incline of }48^{\circ}\\&\text{It is also partially supported by a rope.}\\&\text{The frictional force acting on the block is }207.04N\\&\text{What is the tension felt in the rope?}\\&g=9.81\frac{m}{s^2}\end{align*}$

Possible Answers:

2786.04N

1864.22N

2070.43N

2507.44N

Correct answer:

2507.44N

Explanation:

Normalwrope

$\begin{align*}&\text{To solve a problem of force balance, a good idea is to draw}\\&\text{it out. Since the block is at rest, i.e. stationary, the sum}\\&\text{of forces acting on it must be equal to zero. The forces acting}\\&\text{on it are gravity (in the form of the mass times the gravitational}\\&\text{constant), the force of the rope supporting it, a normal force,}\\&\text{and since it’s on an incline, a frictional force to balance}\\&\text{it all out. Notice that the tension in the rope mitigates some}\\&\text{of the gravitational force (as illustrated in the upper left}\\&\text{corner) to lessen what is applied to the slope:}\\&F_{mass}=m*g\\&F_{normal}=(F_{mass}-F_{rope})*cos(a)\\&F_{friction}=(F_{mass}-F_{rope})*sin(a)\\&F_{rope}=F_{mass}-\frac{F_{friction}}{sin(a)}\\&F_{rope}=2786.04N-\frac{207.04N}{sin(48^{\circ})}\\&F_{rope}=2507.44N\end{align*}$

Report an Error

Example Question #11 : Forces

$\begin{align*}&\text{A block of mass }101kg\text{ rests on an incline of }68^{\circ}\\&\text{It is also partially supported by a rope with a tension of }693.57N\\&\text{What is the frictional force acting on the block from the surface?}\\&g=9.81\frac{m}{s^2}\end{align*}$

Possible Answers:

111.35N

918.66N

275.6N

371.16N

Correct answer:

275.6N

Explanation:

Normalwrope

$\begin{align*}&\text{To solve a problem of force balance, a good idea is to draw}\\&\text{it out. Since the block is at rest, i.e. stationary, the sum}\\&\text{of forces acting on it must be equal to zero. The forces acting}\\&\text{on it are gravity (in the form of the mass times the gravitational}\\&\text{constant), the force of the rope supporting it, a normal force,}\\&\text{and since it’s on an incline, a frictional force to balance}\\&\text{it all out. Notice that the tension in the rope mitigates some}\\&\text{of the gravitational force (as illustrated in the upper left}\\&\text{corner) to lessen what is applied to the slope:}\\&F_{mass}=m*g\\&F_{normal}=(F_{mass}-F_{rope})*cos(a)\\&F_{friction}=(F_{mass}-F_{rope})*sin(a)\\&F_{friction}=(101kg(9.81\frac{m}{s^2})-693.57N)(sin(68^{\circ}))\\&F_{friction}=275.6N\end{align*}$

Report an Error

Example Question #91 : Mechanics Exam

$\begin{align*}&\text{A block of mass }187kg\text{ rests on an incline of }70^{\circ}\\&\text{What is the frictional force acting on the block from the surface?}\\&g=9.81\frac{m}{s^2}\end{align*}$

Possible Answers:

1834.47N

627.43N

63.96N

1723.84N

Correct answer:

1723.84N

Explanation:

Normal

Report an Error

Example Question #12 : Friction And Normal Force

$\begin{align*}&\text{A block of mass }208kg\text{ rests on an incline of }28^{\circ}\\&\text{What is the frictional force acting on the block from the surface?}\\&g=9.81\frac{m}{s^2}\end{align*}$

Possible Answers:

2040.48N

1801.64N

957.95N

183.65N

Correct answer:

957.95N

Explanation:

Normal

Report an Error

View Tutors

Mohammad
Certified Tutor

Jamia Millia Islamia, Master of Science, Physics.

View Tutors

Samar
Certified Tutor

McMaster University, Bachelor's (in progress), Science.

View Tutors

Tom
Certified Tutor

University of Wisconsin-Madison, Bachelor of Science, Atmospheric Sciences and Meteorology. Embry-Riddle Aeronautical Univers...

All AP Physics C: Mechanics Resources

2 Diagnostic Tests 92 Practice Tests Question of the Day Flashcards Learn by Concept

Popular Subjects

Calculus Tutors in Atlanta, Reading Tutors in Miami, Physics Tutors in Atlanta, English Tutors in Phoenix, English Tutors in Atlanta, Calculus Tutors in Los Angeles, SAT Tutors in San Diego, Chemistry Tutors in San Francisco-Bay Area, Chemistry Tutors in Phoenix, Calculus Tutors in San Diego

Popular Courses & Classes

GRE Courses & Classes in Philadelphia, LSAT Courses & Classes in Chicago, ISEE Courses & Classes in Miami, Spanish Courses & Classes in Houston, SSAT Courses & Classes in Denver, ISEE Courses & Classes in Dallas Fort Worth, GMAT Courses & Classes in Los Angeles, GRE Courses & Classes in San Francisco-Bay Area, ISEE Courses & Classes in Atlanta, GRE Courses & Classes in Phoenix

Popular Test Prep

ISEE Test Prep in Denver, ACT Test Prep in Washington DC, GRE Test Prep in Philadelphia, SSAT Test Prep in Washington DC, GMAT Test Prep in New York City, GMAT Test Prep in Los Angeles, GRE Test Prep in Phoenix, LSAT Test Prep in Seattle, GRE Test Prep in San Francisco-Bay Area, SSAT Test Prep in San Francisco-Bay Area

DMCA Complaint

If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.

Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org.

Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.

Please follow these steps to file a notice:

You must include the following:

A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.

Send your complaint to our designated agent at:

Charles Cohn Varsity Tutors LLC
101 S. Hanley Rd, Suite 300
St. Louis, MO 63105

Or fill out the form below:

Do not fill in this field

Contact Information

* Full legal name

Company name

* Phone number

* Email address

Address

* Address1

Address2

* City

* State

* Zipcode

* Country

Complaint Details

* URL of copyrighted work (where your original material is located)

* Please describe the copyrighted work so that it may be easily identified

I am the owner, or an agent authorized to act on behalf of the owner of an exclusive right that is allegedly infringed.

I have a good faith belief that the use of the material in the manner complained of is not authorized by the copyright owner, its agent, or the law.

This notification is accurate.

I acknowledge that there may be adverse legal consequences for making false or bad faith allegations of copyright infringement by using this process.

* Signature (your digital signature is legally binding)

HIGH SCHOOL

GRADUATE SCHOOL

K-8

Search 50+ Tests

math tutoring

science tutoring

foreign languages

elementary tutoring

other

Search 350+ Subjects

AP Physics C: Mechanics : Friction and Normal Force

Study concepts, example questions & explanations for AP Physics C: Mechanics

All AP Physics C: Mechanics Resources

Example Questions

Example Question #2 : Friction

Example Question #2 : Friction

Example Question #3 : Friction

Example Question #4 : Friction

Example Question #5 : Friction

Example Question #4 : Friction

Example Question #11 : Forces

Example Question #91 : Mechanics Exam

Example Question #12 : Friction And Normal Force

All AP Physics C: Mechanics Resources

Report an issue with this question

DMCA Complaint

Contact Information

Address

Complaint Details

Email address:
Your name:
Feedback: