Ball bounces several times on an inclined plane

[carlyn medona]

Homework Statement

A ball falls on an inclined plane of inclination theta from a
height h above the point of impact and makes a perfectly
elastic collision. Where will it hit the plane again ?
Solve the previous problem if the coefficient of restitution
is e. Use theta = 45°, e = .75 and h = 5 m.

Homework Equations

The Attempt at a Solution

I was able to solve first part of the problem and got the distance along the incline to be =8hsinθ. For second part I am getting angle of reflection of ball with normal to be 53 degree but the value in my text is 37degree. but I don't think the angle should be less than theta

 

[yrjosmiel]

perfectly elastic collision

coefficient of restitution is e.

e = 0.75

So is it perfectly elastic or not?

 

[CWatters]

So is it perfectly elastic or not?

They want it solved twice. Once perfectly elastic then again with e=0.75.

 

[carlyn medona]

that's right. In second case it is not elatic

 

[haruspex]

angle of reflection of ball with normal to be 53 degree but the value in my text is 37degree. but I don't think the angle should be less than theta

You are correct. If e < 1 then the angle to the normal of the reflection will be greater than the incident angle to the normal.
I assume you noticed that 37=90-53.

 

[carlyn medona]

yes.

 

[carlyn medona]

okay i finally solved it and got a value of 18.5 m along the incline, thanks for the help.

 

[haruspex]

okay i finally solved it and got a value of 18.5 m along the incline, thanks for the help.

Good. (I get 18.56.)

 

[carlyn medona]

Thank you for your help.