Block projected up inlcline with initial speed

In summary, the conversation involved finding the time it takes for a block on an inclined plane to go up and return to its starting point. The relevant equations and forces were discussed, including the role of friction and the need to carefully consider the signs in the equations of motion. Ultimately, it was determined that the equations of motion would be different for the block moving up the plane versus moving down the plane.
  • #1
Cocoleia
295
4

Homework Statement


I have a block on an inclined plane (the angle is 40). The block is projected with an initial speed of 2m/s and μ=0.05. I need to find the time it takes the block to go up the inclined plane and return to the point it started out.

Homework Equations

The Attempt at a Solution


I know that the force of friction will be μmgcosθ. Usually, the force bringing the block down the plane is mgsinθ.
I figure that I will need to find the acceleration and then use the equations of motion to find t, since the final speed at the top of the plane will be 0. I am having trouble setting up my equations.
Would it be that:
ma = -mgsinθ+ μmgcosθ
 
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  • #2
You're on the right track. Keep in mind that friction always opposes the direction of motion. So while the block is moving upslope, friction is directed downslope as is the relevant component of the gravitational force. In other words, be careful of the signs that you apply to the friction term.
 
  • #3
gneill said:
You're on the right track. Keep in mind that friction always opposes the direction of motion. So while the block is moving upslope, friction is directed downslope as is the relevant component of the gravitational force. In other words, be careful of the signs that you apply to the friction term.
Ok, I've been working on it and I think that going up the plane it will be: ma = -mgsinθ-μmgcosθ and going down the plane it would be ma=-mgsinθ+μmgcosθ since I put the axis as being x directed up the plane and y directed like the normal
 
  • #4
Looks good so far!
 

Related to Block projected up inlcline with initial speed

1. What is the definition of "block projected up incline with initial speed"?

"Block projected up incline with initial speed" refers to a physical scenario in which a block is launched from the bottom of an inclined plane with a certain initial speed, and then travels up the incline due to the force of gravity acting upon it.

2. What factors affect the motion of the block in this scenario?

The motion of the block is affected by several factors, including the initial speed at which it is launched, the angle of the incline, the mass of the block, and the force of gravity.

3. How can the motion of the block be calculated?

The motion of the block can be calculated using principles of physics, such as Newton's laws of motion and the equations for projectile motion. The specific calculations will depend on the given values for the factors mentioned in the previous question.

4. What is the significance of this scenario in the field of physics?

This scenario is significant because it allows for the application of fundamental physics principles, such as projectile motion and the effects of gravity, in a real-world scenario. It also demonstrates the connection between different areas of physics, such as mechanics and kinematics.

5. Can this scenario be observed in everyday life?

Yes, this scenario can be observed in everyday life in various forms, such as a ball rolling up a ramp or a car driving up a hill. It is a common occurrence that can be explained and predicted using the principles of physics.

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