Question

1. A wheel starts from rest, when a torque applied to it accelerates it at 40 rad/s . If allowed to accelerate for 5s, how fast would the wheel be spinning?

2. A wheel starts from rest, when a torque applied to it accelerates it at 40 rad/s . If allowed to accelerate for 5s, how much, in radians, would it rotate?

3. A car has wheels with a radius of 20cm. If the car is initially driving at 25 m/s, what angular acceleration would be required to stop the car within 75m?

4. A force, under any circumstance, will produce a torque. (a) True (b) False

Answer 1

Problem - 1

Given is:-

Angular acceleration

Time  

Initial speed  

Now,

using first equation of motion we get

by plugging all the values we get

which gives us

Problem - 3

Radius r = 0.20 m

Initial speed u = 25 m/s

Distance covered by car before stopping s = 75 m

Now,

Using third equation of motion we get

by plugging all the values we get

which gives us

Negative sign indicates that it is actually decleration

Thus the angular acceleration will be

by plugging the values we get

which gives us

Problem - 4

correct answer = False

When the applied force is parallel to r vector