Which is a result of using a machine?
1 answer:
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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
The crate moves at constant velocity, this means that its acceleration is zero, so the net force acting on the crate is zero (Newton's second law).
There are only two forces acting on the crate: the force F applied by the worker and the frictional force, acting in the opposite direction:
, where 
is the coefficient of friction and 
is the mass of the crate. Since the net force should be equal to zero, the two forces must have same magnitude, so we have:
And so, this is the force that the worker must apply to the crate.
There are only two forces acting on the crate: the force F applied by the worker and the frictional force, acting in the opposite direction:
And so, this is the force that the worker must apply to the crate.