Atrain is accelerating at a rate of 2m/s2. if it's initial velocity is 20 m/s , what is its velocity after 30 seconds

Aballet student who learns with the of his instructor is demonstrating learning.

Amachinist turns the power on to a grinding wheel, at rest, at time t = 0 s. the wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 96 rad/s. the wheel is run at that angular velocity for 40 s and then power is shut off. the wheel slows down uniformly at 1.5 rad/s2 until the wheel stops. in this situation, the time interval of deceleration is closest to:

How is the ideal mechanical advantage of a wheel and axle calculated?