Physics Hwk. Problem: Frictional Force

NBMagnitude of acceleration: 6.72 m/s^2In summary, to solve this problem, first calculate the downward and horizontal components of the force F. Then, use the downward component to determine the normal force, which in turn determines the horizontal frictional force. Finally, subtract the horizontal frictional force from the horizontal component of F to find the acceleration of the block.
  • #1
shawonna23
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I am really stuck on how to even start solving this problem, can someone help me please!

A 2.5 kg block is pushed along a horizontal floor by a force F of magnitude 17 N at an angle = 35° with the horizontal. The coefficient of kinetic friction between the block and floor is 0.25.

a.Calculate the magnitude of the frictional force on the block from the floor.
b.Calculate the magnitude of the acceleration of the block.
 
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  • #2
shawonna23 said:
A 2.5 kg block is pushed along a horizontal floor by a force F of magnitude 17 N at an angle = 35° with the horizontal. The coefficient of kinetic friction between the block and floor is 0.25.

a.Calculate the magnitude of the frictional force on the block from the floor.
b.Calculate the magnitude of the acceleration of the block.
The force F provides a downward component and a horizontal component. Work out the magnitude of each component.

The downward component provides additional normal force (in addition to mg). The normal force determines the horizontal frictional force:

The acceleration is determined by the horizontal component of F minus the horizontal friction force.

AM
 
  • #3


To start solving this problem, you need to first draw a free body diagram of the block. This will help you visualize all the forces acting on the block. The force F is the pushing force applied at an angle of 35°, and the frictional force is acting in the opposite direction of the motion. The weight of the block, which is equal to its mass (2.5 kg) multiplied by the gravitational acceleration (9.8 m/s^2), is acting downwards.

Now, to calculate the magnitude of the frictional force, you can use the formula Ff = μN, where μ is the coefficient of kinetic friction and N is the normal force. The normal force is equal to the weight of the block, so we can substitute that in the formula. Thus, Ff = (0.25)(2.5 kg)(9.8 m/s^2) = 6.125 N. This is the magnitude of the frictional force on the block from the floor.

To calculate the acceleration of the block, we can use Newton's Second Law, which states that the net force on an object is equal to its mass multiplied by its acceleration (F = ma). In this case, the net force is the pushing force F minus the frictional force Ff, so we can write the equation as F - Ff = ma. We know the values for F and Ff, so we can substitute them in the equation. Thus, 17 N - 6.125 N = (2.5 kg)a. Solving for a, we get a = 4.35 m/s^2. This is the magnitude of the acceleration of the block.

I hope this helps you get started on solving the problem. Remember to always draw a free body diagram and use relevant equations to solve physics problems. Good luck!
 

1. What is frictional force?

Frictional force is the resistance force that occurs when two surfaces come into contact with each other and are moving relative to one another.

2. What factors affect the magnitude of frictional force?

The magnitude of frictional force is affected by the nature of the surfaces in contact, the force pressing the surfaces together, and the relative speed of the surfaces.

3. How does frictional force impact motion?

Frictional force acts in the opposite direction of motion, which means it can slow down or stop an object's motion. It also causes objects to heat up due to the energy lost during the frictional process.

4. Can frictional force be reduced or eliminated?

Frictional force can be reduced by using lubricants or by choosing materials with smoother surfaces. It cannot be completely eliminated, as it is a natural force that is present whenever two surfaces are in contact.

5. How is frictional force related to Newton's laws of motion?

Frictional force is related to Newton's first law of motion, which states that an object will remain at rest or in motion at a constant velocity unless acted upon by an external force. Frictional force is also related to Newton's second law of motion, which states that the net force on an object is equal to its mass times its acceleration.

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