Answer:
Less than 18000N
Explanation:
Given

This question will be answered using Newton's third law.
Understanding this law, it implies that reaction force is equal and opposite to the force exerted.
This implies that;
If the force exerted on the ball is 18000N
the force exerted is -18000N
So, the option that answers the question is less than 18000N because -18000N < 18000N
Answer:
240 ohms
Explanation:
From Ohms law we deduce that V=IR and making R the subject of the formula then R=V/I where R is resistance, I is current and V is coltage across. Substituting 120 V for V and 0.5 A for A then
R=120/0.5=240 Ohms
Alternatively, resistance is equal to voltage squared divided by watts hence 
With "toward the wall" designated as the positive direction, the average acceleration felt the ball in the 0.0158 s of contact with the wall is

The refractive index is the ratio of the speed in a vacuum to the speed of light in the given medium. If the refractive index is too low, there will not be a large bending, or deviation, of the light beam from its original path.
The small deviation will make it difficult to carry out the experiment, and is more likely to cause errors. Therefore, larger refractive indexes should be used, in order to ensure that the bending of the light beams is easily traceable.