In order to compute the torque required, we may apply Newton's second law for circular motion:
Torque = moment of inertia * angular acceleration
For this, we require the angular acceleration, α. We may calculate this using:
α = Δω/Δt
The time taken to achieve rotational speed may be calculated using:
time = 1 revolution * 2π radians per revolution / 3.5 radians per second
time = 1.80 seconds
α = (3.5 - 0) / 1.8
α = 1.94 rad/s²
The moment of inertia of a thin disc is given by:
I = MR²/2
I = (0.21*0.1525²)/2
I = 0.002
τ = 1.94 * 0.002
τ = 0.004
The torque is 0.004
The acceleration of the car will be needed in order to calculate the time. It is important to consider that the final speed is equal to zero:

We can clear time in the speed equation:

If you find some mistake in my English, please tell me know.
The answer is d. Wavelength
Answer:

Explanation:
Since the object is under a circular motion, according to Newton's second law, when the object is at the top of the circle we have:

Where
is the centripetal force and is given by:

Replacing and solving for T:


Explanation:
Given:


The cross product
is given by


