Answer: 
Explanation:
Given
Mass of child 
speed of child is 
Moment of inertia of merry go round is 
radius 
Conserving the angular momentum
Answer:
t = 5.89 s
Explanation:
To calculate the time, we need the radius of the pulley and the radius of the sphere which was not given in the question.
Let us assume that the radius of the pulley (
) = 0.4 m
Let the radius of the sphere (r) = 0.5 m
w = angular speed = 150 rev/min = (150 × 2π / 60) rad/s = 15.708 rad/s
Tension (T) = 20 N
mass (m) = 3 kg each
Substituting values:
I’m pretty sure it’s, B. An Electric Motor. I apologize in advance if it’s incorrect.
Answer:
Steven has to row at a speed to reach the same horizontal spot at the other side of the river is, V = 6 m/s
Explanation:
Given data,
The river flowing south at the rate, v = 3 m/s
To reach the other side directly across the river, he aims the raft, Ф = 30°
The speed of his raft across the river is given by the formula,
V = v / Sin Ф
= 3 / Sin 30°
= 6 m/s
Steven has to row at a speed to reach the same horizontal spot at the other side of the river is, V = 6 m/s
The cheetah's speed is 100x and
The gazelle's speed is 80x + 70.
Set the two equations equal to each other:
100x = 80x +70 (then subtract 80x from both sides).
20x = 70 (then divide by 20).
X =3.5.
The cheetah catches the gazelle after 3.5
