Answer:
α=9.42 rad/s T= 0.014 rad/s
Explanation:
Low speed= Wi=3 rps = 3*2*π rad/s= 6π rad/sec
Medium speed= Wf= 9 rps= 9*2*π rad/sec= 18 rad/sec
time= t= 4 sec
Angular acceleration=α=
⇒α=(18 π - 6 π)/4
⇒α=9.42 rad/s
b).
Rotational inertia= I = 1.5*10^-3 kg-m^2
Net torque= T = I*α = (1.5*10^-3) * (9.42) rad/s^2
⇒T= 0.014 rad/s^2
The apparent velocity is B) 48 m/s north
Explanation:
Here we have a problem of relativity of velocities.
In fact, the train is travelling north at a speed of
where this velocity is measured with respect to the ground.
At the same time, a passenger on the train is walking towards the rear (so, south) at a velocity of
where this velocity is measured with respect to the train, which is in motion in the opposite direction.
Therefore, the apparent velocity of the passenger with respect to an observer standing on the ground is:
And the direction is north, since this number is positive.
Learn more about velocity:
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