Answer:
There are three ways an object can accelerate: a change in velocity, a change in direction, or a change in both velocity and direction.
Explanation:
Answer
Radius of the wheel r = 2.1 m
Moment of inertia I = 2500 Kg m²
Tangential force applied F = 18 N
Time interval t = 16 s
Initial angular speed ω1 = 0
Final angular speed ω2 = ?
Let α be the angular acceleration.
Torque applied τ = Iα
F r = Iα
Angular acceleration α = F r/I
= 
= 0.015 rad/s²
(a)From rotational kinematic relation
Final angular speed ω₂ = ω₁ + αt
= 0 + (0.015 rad/s^2 * 16 s)
= 0.24 rad/s
(b) Work done W = 0.5 Iω₂² - (1/2)Iω₁²
= 0.5*( 2500 Kg m²)(0.24 rad/s)^2 - 0
= 72 J
(c) Average power supplied by the child P = W/t = 
= 4.5 watt
Answer:
By the information given, I am not sure how the event has played out. However, using common knowledge, I can give a scenario of how it may play out.
When removing the first block (the foundation), gravity will pull the other blocks down, as the strength of gravity exceeds that of the strength of air holding it up. This means that all the blocks on top would fall.
By definition of Newton's 1st - 3rd laws, the blocks would not move unless a force is given to it (i.e., removing the bottom block, which causes gravity). Gravity would pull the other blocks downwards. This would lead to the falling of the stack of blocks.
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