Part A: A typical automobile tire has a mass of about 9 kg and is about 0.6 mete
ID: 1615696 • Letter: P
Question
Part A:
A typical automobile tire has a mass of about 9 kg and is about 0.6 meter in diameter or 0.3 meter radius. Its moment of inertia is therefore around 0.8 kg-m2 if most of its mass is close to the outside tread. If the tire is free to spin and a force of 10 newtons is applied to the edge to give it some angular momentum, how fast would it be turning after 1 second?
a. 1.2 revolutions per second
b. 47 revolutions per second
c. 3.8 revolutions per second
d. 0.6 revolutions per second
Part B:
Starting from a height of 15.3 meters, and falling near Earth's surface, how fast will you be going when you hit the ground? Give your answer in m/s.
Hint: First find how long it takes, then from that find how fast you will be going. Assume the acceleration of gravity is 9.8 m/s2.
Explanation / Answer
(A)
r = 0.3 m
F = 10 N
I = 0.8 kg-m2
t = I*?
r*F = I*?
0.3 * 10 = 0.8 * ?
? = 3.75 rad/s^2
? = ?o + ?*t
? = 0 + 3.75 * 1
? = 3.75 rad/s
Converting to revoution,
? = 0.6 revolutions per second
(B)
h = 15.3 m
g = 9.8 m/s^2
u = 0
v^2 = u^2 + 2*a*h
v^2 = 0 + 2*9.8*15.3
v = 17.32 m/s