Blocks, Friction Forces and Acceleration

In summary, the block will move under the influence of the force and the net force will be the applied horizontal force minus the kinetic friction force.
  • #1
sunnyorange
7
0
I am having trouble with this problem:
A block whose weight is 50.0N rests on a horizontal table. A horizontal force of 25.0 N is applied to the block. The coefficients of static and kidnetic friction are 0.510 and 0.350 respectively. Will the Block move under the influence of the force and if so, what will be the block's acceleration?
What I have so far:
1. Fs=mu sN
=0.510*50
=25.5 N
25.5 N>25.0 N, therefore the block will move under the influence of the force.
2. Finding acceleration
I know I have to find the net force then use that in the second law equation. How do I do that.
I have kinetic force=17.5, mass=50/9.8=5.10 kg.
Please help!:cry:
 
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  • #2
sunnyorange said:
25.5 N>25.0 N, therefore the block will move under the influence of the force

You might want to look at this again. Which one was the force due to static friction?
 
  • #3
You are correct so far.

Think Newton's second law: the pulling force stays the same, but now instead of static friction, there is kinetic friction. What's the net force?
 
  • #4
Would the net force be: applied horizontal force-kinetic friction force?
 
  • #5
yes, that's correct (there are two other forces in the vertical direction, but Normal force and weight will balance each other in *this* situation).
 

FAQ: Blocks, Friction Forces and Acceleration

1. What is a block?

A block is a solid object with flat surfaces that can be used to represent objects in physics experiments or problems. It is often used to simplify complex objects and focus on specific characteristics, such as mass and shape.

2. What is friction force?

Friction force is a force that resists the movement of one object over another. It occurs when two surfaces are in contact and can be affected by factors such as the type of surfaces, the force pressing the surfaces together, and the presence of lubricants.

3. How does friction affect acceleration?

Friction can decrease the acceleration of an object by opposing its motion. This is because friction force acts in the opposite direction of an object's motion, creating a counterforce that needs to be overcome for the object to continue accelerating.

4. Can friction force ever increase acceleration?

No, friction force can never increase acceleration. It can only decrease or oppose an object's acceleration.

5. How can we reduce friction force?

Friction force can be reduced by using lubricants, such as oil or grease, between two surfaces. It can also be reduced by using smoother or more slippery surfaces, or by decreasing the force pressing the surfaces together.

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