I think the answer is c but I’m not sure
It’s D. An enlargement (hope this helps!)
1) At the moment of being at the top, the piston will not only tend to push the penny up but will also descend at a faster rate at which the penny can reach in 'free fall', in that short distance. Therefore, at the highest point, the penny will lose contact with the piston. Therefore the correct answer is C.
2) To solve this problem we will apply the equations related to the simple harmonic movement, hence we have that the acceleration can be defined as

Where,
a = Acceleration
A = Amplitude
= Angular velocity
From a reference system in which the downward acceleration is negative due to the force of gravity we will have to



From the definition of frequency and angular velocity we have to




Therefore the maximum frequency for which the penny just barely remains in place for the full cycle is 2.5Hz
Answer:
The change on the second particle is
.
Explanation:
The period of revolution of the particle in the magnetic field is given by the formula as follows :

It is given that the magnetic field is uniform. The mass of the second particle is the same as that of a proton but thecharge of this particle is different from that of a proton.

If both particles take the same amount of time to go once around their respective circles. So,

So, the change on the second particle is
.
Speed is different from velocity. Velocity is a vector quantity and has a direction. Speed is a scalar quantity and does not require a direction. The answer must be D).