That is because there are other forces like the friction forces that apply differently on both of them. The frictional forces applied to the sled are smaller than they are on the father, for example, so it's possible for him to pull it.
Answer:
D) True. the protostar rotates more quickly.
Explanation:
If the system is isolated, the angular momentum must be retained.
Initial
L₀ = I w₀
Final
= 
L₀ =
I w₀ =
= I / w₀
In general, the radius of the cloud decreases significantly to form the star, the moment of inertia must decrease, so the angular velocity must increase
Let's examine the answers
A) False. The opposite happens
B) False. Speed changes
C) False. For this there must be an external force, which does not exist
D) True. You agree with the above
A). nuclear
No. There were batteries long long before we learned
how to use nuclear energy. Also, there is no danger of
exposure to radioactivity when you're working with a battery.
b). mechanical
No. A battery has no moving parts.
c). gravitational
No. No matter how high you take a battery in an airplane, or
how far you lower it into a mine-shaft, its characteristics don't
change. In fact, batteries even work on things that are in orbit.
d). chemical
Bingo.
Answer:
Explanation:
dU= dq+w
dU is change in internal energy of the system
dq is the amount heat added or released by the system which be positive or negative respectivelý
And w is the amount of work done by the system or on the system which will be positive or negative respectively.
Hence,
dU= 250+80= 330 J
The change will be positive
