Solve these problems: 1/ A bicycle wheel is rotating at 50 when the cyclist begi
ID: 1970896 • Letter: S
Question
Solve these problems:1/ A bicycle wheel is rotating at 50 when the cyclist begins to pedal harder, giving the wheel a constant angular acceleration of 0.46
A/ What is the wheel's angular velocity, in rpm, 12 later? By ?
Express your answer using two significant figures.
B/ How many revolutions does the wheel make during this time? By revolutions?
Express your answer using two significant figures.
2/ A long string is wrapped around a 6.8- -diameter cylinder, initially at rest, that is free to rotate on an axle. The string is then pulled with a constant acceleration of 2.0 until 1.5 of string has been unwound. If the string unwinds without slipping, what is the cylinder's angular speed, in rpm, at this time? By ?
Express your answer using two significant figures.
3/ Astronauts use a centrifuge to simulate the acceleration of a rocket launch. The centrifuge takes 20.0 to speed up from rest to its top speed of 1 rotation every 1.50 . The astronaut is strapped into a seat 6.80 from the axis.
A/ What is the astronaut's tangential acceleration during the first 20.0 ?
B/ How many g's of acceleration does the astronaut experience when the device is rotating at top speed? Each 9.80 of acceleration is 1 g.
4/ An electric-generator turbine spins at 3800 . Friction is so small that it takes the turbine 24.0 to coast to a stop.
How many revolutions does it make while stopping? By rev ?
Explanation / Answer
wo = 50 rpm = 5.236 rad/s
a = 0.46 rad/s^2
t = 12 sec
A.
w = wo +at
= 5.236 + 0.46 x 12
= 10.756 rad/s
= 102.71 rpm
B
= wot + 0.5at^2
= 5.236 x 12 + 0.5 x 0.46 x 12^2
= 95.952 rads
= 15.27 rev