A 10 kg lead brick falls from a height of 2.0m.
a) Find its momentum as it reaches the ground.
b) What impulse is needed to bring the brick to rest?
c) The brick falls onto a carpet, 1.0 cm thick. Assuming the force stopping it is constant, find the average force the carpet exerts on the brick.
d) If the brick falls onto a 5.0 cm foam rubber pad, what constant force is needed to bring it to rest?

Please help, I have tried.. and so far I got a) -40 kg x m/s ..Not sure if even that is right

Question

A 10 kg lead brick falls from a height of 2.0m. 
a) Find its momentum as it reaches the ground. 
b) What impulse is needed to bring the brick to rest?
c) The brick falls onto a carpet, 1.0 cm thick. Assuming the force stopping it is constant, find the average force the carpet exerts on the brick.
d) If the brick falls onto a 5.0 cm foam rubber pad, what constant force is needed to bring it to rest?

Please help, I have tried.. and so far I got a) -40 kg x m/s ..Not sure if even that is right

souvik · Answer

first find the velocity of the brick as it reaches the ground..

souvik · Answer

@brightdiwa

souvik · Answer

$$v^2=u^2+2gh$$
u=initial velocity=0 m/s 
v=final velocity
g=10 m/s^2
h=distance=2.0 m
$$v=2\sqrt{10}$$ m/s
so the momentum is mass*velocity=$20\sqrt{10}$

anonymous · Answer

where did u get that value for g?

unklerhaukus · Answer

$$g\approx9.8[\text {m/s}^2]\sim10[\text {m/s}^2]$$

souvik · Answer

you can use g=9.8 m/s^2...

anonymous · Answer

A 60 kg dancer leaps 0.32m high. 
With what momentum does the dancer reach the ground?
What impulse is needed to make a stop?
As the dancer lands, the knees bend, lengthing the stopping time to 0.050 seconds. FInd  the average force exerted on the body. 
Compare the stopping force to the performer's weight.


I need help on this question
Any help and explanation is appreciated