Please I want someone to answer it clearly and step by step When a spinning ice
ID: 1560841 • Letter: P
Question
Please I want someone to answer it clearly and step by step
When a spinning ice skater brings her arms in close to her body she spins faster because: (a) Her rotational inertia decreases. (b) Rotational momentum is not conserved. (c) Her rotational momentum increases. (d) The force acting on her is greater. Answer:_____ A satellite put into orbit around the earth (a) Does not experience the effect of gravity. (b) Falls continuously around the earth. (c) Has no force acting on it. (d) Requires constant power from a rocket to keep it in orbit. Answer:____ You are standing near the center of a playground merry-go-round that is rotating at constant rotational speed. As you move outwards towards the edge: (a) The combined rotational inertia of you and the merry-go-round decreases. (b) The rotational speed of the merry-go-round remains the same. (c) Rotational momentum is not conserved. (d) The rotational speed of the merry-go-round decreases. Answer:____ When you walk (a) You and the floor push on each other equally. (b) The floor pushes on you with a greater force than you push on the floor. (c) You push on the floor with a greater force than the floor pushes on you. (d) Only you push on the floor because a floor can't push on you. Answer:_____ You stand on a bathroom scale in an elevator. The scale will read less than your normal weight when the elevator (a) Starts suddenly upward. (b) Travels upward at constant speed. (c) Travels downward at constant speed. (d) Slows down to stop at the second floor, after rising from the first floor. Answer: _____Explanation / Answer
6. angular momentum ( I w ) is conserved and in this process, moment of inertia of her decreases hence angular speed increases.
Ans. (A)
7. for satellite moving in circular orbit,
Gravitational force = mass * centrieptal acceleration = 0
there is gravitational force acting on it but that used in providing cetripeta acceleration.
hence it does not experience the effect of gravity.
Ans(A)
8. as you move toward away from center.
moment of inertia of system increase. (I = I_round + m r^2)
and angular momentum (I w) of system will be conserved.
hence rotational speed will decrease.
Ans(d)
9. from newton's 3rd law,
you and the floor push on each other equally.
Ans(a)
10. N - m g = m a
N = mg + ma
N is less than mg
that means a is negative.
so a is downwards.
Ans(d)