I think its D but I'm not sure :/
In a real system of levers, wheel or pulleys, the AMA (actual mechanical advantage) is less than the IMA (ideal mechanical advantage) because of the presence of friction.
In fact, the IMA and the AMA of a machine are defined as the ratio between the output force (the load) and the input force (the effort):

however, the difference is that the IMA does not take into account the presence of frictions, while the AMA does. As a result, the output force in the AMA is less than the output force in the IMA (because some energy is dissipated due to friction), and the AMA is less than the IMA.
Answer:

Explanation:
According to the free-body diagram of the system, we have:

So, we can solve for T from (1):

Replacing (3) in (2):

The electric force (
) is given by the Coulomb's law. Recall that the charge q is the same in both spheres:

According to pythagoras theorem, the distance of separation (r) of the spheres are given by:

Finally, we replace (5) in (4) and solving for q:

Answer:
The magnitude of the force exerted by the ball on the catcher is 1.9 × 10² N
Explanation:
Hi there!
Let´s find the acceleration of the ball that makes it stop when caught by the catcher. The acceleration can be calculated from the equation of velocity considering that it is constant:
v = v0 + a · t
We know that initially the ball was traveling at 25 m/s, so, if we consider the position of the catcher as the origin of the frame of reference, then, v0 = -25 m/s. We also know that it takes the ball 20 ms (0.02 s) to stop (i.e. to reach a velocity of 0). Then using the equation of velocity:
v = v0 + a · t
0 m/s = -25 m/s + a · 0.020 s
25 m/s/ 0.020 s = a
Now, using the second law of Newton, we can calculate the force exerted by the catcher on the ball:
F = m · a
Where:
F = force.
m = mass of the ball.
a = acceleration.
F = 0.150 kg · (25 m/s/ 0.020 s) = 1.9 × 10² N
According to Newton´s third law, the force exerted by the ball on the catcher will be of equal magnitude but opposite direction. Then, the force exerted by the ball on the catcher will have a magnitude of 1.9 × 10² N.