Where brick hits ground after sliding off a roof w/ friction

In summary, the problem involves a brick sliding off a roof with a kinetic friction value of 0.28. The roof is 7.0 m above the ground and the edge of the roof is 4.0 m above the ground. To solve the problem, the force diagram of the brick is drawn and the acceleration down the roof is determined. Using the coefficient of kinetic friction, the frictional force is calculated. From there, the speed at which the brick leaves the roof can be determined.
  • #1
isabelrose
2
0

Homework Statement


Brick is sliding off a roof, starts at the peak of the roof (7.0 m above ground), slides down roof with kinetic friction value of 0.28, very edge of roof is 4.0 m above ground. Where does the brick land on the ground?
Please see image - http://imgur.com/wNdtlWD

Homework Equations

The Attempt at a Solution


I attempted the solution by: [/B]
drawing force diagram of brick (@ = angle of incline, 30 degrees) which gives the acceleration down (acceleration down the roof = positive direction) the roof by:
ma = mgsin@ - frictional force
ma = mgsin30 - 0.28

Now should I just continue to solve for the acceleration and then treat this as a projectile? If so, can someone walk me through it?


Thanks!
 
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  • #2
0.28 is not the frictional force. It is the coefficient of kinetic friction. How do you obtain the frictional force from the coefficient?
 
  • #3
haruspex said:
0.28 is not the frictional force. It is the coefficient of kinetic friction. How do you obtain the frictional force from the coefficient?
Oh yeah!
The frictional force (Ff) = coefficient of kinetic friciton * Fn = 0.28 * mgcos@
 
  • #4
isabelrose said:
Oh yeah!
The frictional force (Ff) = coefficient of kinetic friciton * Fn = 0.28 * mgcos@
Good.
So, at what speed does it leave the roof?
 

1. How does friction affect the movement of a brick sliding off a roof?

The force of friction between the brick and the ground will slow down the brick's sliding motion, eventually bringing it to a stop.

2. What factors determine where the brick will hit the ground?

The height of the roof, the angle at which the brick is released, the coefficient of friction between the brick and the roof, and any external forces (such as wind) can all affect where the brick will hit the ground.

3. Can the location where the brick will hit the ground be accurately predicted?

Yes, using principles of physics and mathematics, the location where the brick will hit the ground can be calculated with a high degree of accuracy.

4. How does the mass of the brick affect its movement?

The mass of the brick will affect the force of friction acting upon it. A heavier brick will experience a greater force of friction, resulting in a shorter sliding distance and a closer impact location to the base of the roof.

5. Is there a way to reduce the impact force of the brick hitting the ground?

Yes, by increasing the coefficient of friction between the brick and the roof, the brick will experience more friction and slow down more quickly, resulting in a lower impact force when it reaches the ground.

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