A50n brick is suspended by a light string from a 30kg pulley which may be considered a solid disk with radius 2.0m. the brick is released from rest and falls to the floor below as the pulley rotates. it takes 4 seconds for the brick to hit the floor. i) what is the tension in newtons in the string well the brick is falling? ii) what is the magnitude of the angular momentum in kg*m^2/s of the pulley at the instant the brick hits the floor?

Brick is held at a position which is at height 2 m from the floor

Now it is released from rest and hit the floor after t = 4 s

Now the acceleration of the brick is given by

a)

Now in order to find the tension in the string

we can use Newton's law

part b)

Now for the pulley

moment of inertia=

m = 30 kg

R = 2 m

I =

I = 60 kg m^2

Now the angular speed just before brick collide with the floor

v = 1 m/s

Now we will have

L = angular momentum = I w =

L = 60 *

L = 30 kg m^2/s

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

d. platinum would have the greatest temperature increase because it has the lowest specific heat.