AP Physics B Multiple Choice Newtonian (1 prob)

In summary, the block slides along the table due to the horizontal force and the vertical force. The coefficient of kinetic friction between the block and the table is 0.2, so the frictional force exterted on the block is most nearly 1 N.
  • #1
ChickenChakuro
32
0
Hi guys, I need help with the following problem I couldn't figure out:

1) A block of mass 2 kg slides along a horizontal tabletop. A horizontal applied force of 12 N and a vertical applied force of 15 N act on the block. If the coefficient of kinetic friction between the block and the table is 0.2, the frictional force exterted on the block is most nearly
A) 1 N
B) 3 N
C) 4 N
D) 5 N
E) 7 N

The answer is E. Why?
 
Last edited:
Physics news on Phys.org
  • #2
What thoughts did u have about it?Something must have crossed your mind...

To get their answer,take g=10ms^{-2}.

Daniel.
 
  • #3
I thought that the frictional force was given by the equation Ff = mu*m*g*cos(theta). But that only comes out to 1/5*2*10=4N. So I have no idea how to factor in the vertical force.
 
  • #4
What "cos" are u dreaming about ?All forces have right angles between them."cos 90°=0",IIRC.

Daniel.
 
  • #5
Sorry I still don't understand. Can someone please help me get this concept?
 
  • #6
The problem is ambiguous,because it doesn't specify the direction of the forces...Assume the vertical force pushes the body into the table (it has the same direction & sense as the gravity force).

Since the body is moving,u have to know what is the expression of the kinetic friction force.

Daniel.
 
  • #7
You are correct, the vertical force is pushing the block into the table. I believe the force of kinetic friction is mu * Normal Force. Normal force here would be 15 N, right, so F kinetic friction = 3? Bah, I don't know.
 
  • #8
No.In the table,the pressing force is the 15N external force and the 20N force due to gravity attraction.Therefore,the normal force is 15+20=35N

Daniel.
 
  • #9
Yes, but why isn't there an opposite reaction from the table upwards into the block of the same force of the block's weight, 20 N?
 
  • #10
That's part of the reaction force,called NORMAL FORCE...

Daniel.
 
  • #11
Ok thank you for your help :smile:
 

Related to AP Physics B Multiple Choice Newtonian (1 prob)

1. How many questions are on the AP Physics B Multiple Choice Newtonian (1 prob) exam?

The AP Physics B Multiple Choice Newtonian (1 prob) exam consists of 35 questions.

2. How much time is allotted for the AP Physics B Multiple Choice Newtonian (1 prob) exam?

Students have 45 minutes to complete the AP Physics B Multiple Choice Newtonian (1 prob) exam.

3. What topics are covered on the AP Physics B Multiple Choice Newtonian (1 prob) exam?

The AP Physics B Multiple Choice Newtonian (1 prob) exam covers topics such as kinematics, forces, energy, momentum, circular motion, and gravitation.

4. Are calculators allowed on the AP Physics B Multiple Choice Newtonian (1 prob) exam?

Yes, students are allowed to use a calculator on the AP Physics B Multiple Choice Newtonian (1 prob) exam. However, only non-graphing, scientific calculators are permitted.

5. How is the AP Physics B Multiple Choice Newtonian (1 prob) exam scored?

The AP Physics B Multiple Choice Newtonian (1 prob) exam is scored on a scale of 1 to 5, with 5 being the highest score. The number of questions answered correctly is converted to a scaled score based on statistical analysis of previous exams.

Similar threads

  • Introductory Physics Homework Help
Replies
13
Views
1K
  • Introductory Physics Homework Help
Replies
22
Views
4K
  • Introductory Physics Homework Help
Replies
4
Views
3K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
7
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
2
Replies
45
Views
5K
  • Introductory Physics Homework Help
Replies
9
Views
3K
  • Introductory Physics Homework Help
Replies
7
Views
2K
  • Introductory Physics Homework Help
Replies
2
Views
742
Back
Top