The laws of motion - rock sliding on a roof

[haha1234]

The laws of motion -- rock sliding on a roof

Homework Statement

One side if the roof of a house slopes up at 37.0°.A roofer kicks a round,flat rock that has been thrown onto the roof by a neighborhood child.The rock slides straight up the incline with an initial speed of 15ms^-1.The coefficient of kinetic friction between the rock and the roof is 0.400.The rock slides 10.0m up the rock and the roof crosses the ridge and goes into free fall, following a parabolic trajectory above the far side of the roof,with negligible air resistance.Determine the maximum height the rock reaches above the point where it was kicked.

Homework Equations

The Attempt at a Solution

Are there anything wrong?
Let the maximum height the rock reaches above the point where it was kicked be h.
1/2mv²=mgh+fs
1/2m(15)²=9.8mh+0.4xmx9.8xcos37°x10

 

[Tanya Sharma]

What is the acceleration the rock will undergo while sliding up the roof ? From this calculate the velocity of the rock just before it leaves the roof. What do you get ?

Edit :You can also approach this problem using Work Energy concepts .

 

[SteamKing]

Angles are not measured in degrees Celsius.

 

[haruspex]

Let the maximum height the rock reaches above the point where it was kicked be h.
1/2mv²=mgh+fs
1/2m(15)²=9.8mh+0.4xmx9.8xcos37x10

That looks right to me.

 

[TSny]

Are there anything wrong?
Let the maximum height the rock reaches above the point where it was kicked be h.
1/2mv²=mgh+fs

Does the rock have any kinetic energy when it reaches maximum height?

 

[haruspex]

Does the rock have any kinetic energy when it reaches maximum height?

Do I still get to keep my award for the year?

 

[TSny]

Do I still get to keep my award for the year?

(Definitely!)

 

[haha1234]

Does the rock have any kinetic energy when it reaches maximum height?

I think...no.
This is because all the energy will convert to potential energy.

 

[TSny]

I think...no.
This is because all the energy will convert to potential energy.

What would happen to the rock (which is traveling along a parabolic arc) if it came to rest at its highest point?

 

[haha1234]

What would happen to the rock (which is traveling along a parabolic arc) if it came to rest at its highest point?

Thanks!I can find the correct answer now!

 

[adjacent]

Angles are not measured in degrees Celsius.

:rofl: