Gravitational force is determined by mass
Answer: Option B
<u>Explanation:</u>
According to Universal law of gravity, the gravitational force is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance between the objects.

Where,
G – gravitational constant = 
= masses of two objects
r – distance between the objects
So, as per this law, the gravitational force is found by mass.
Answer:
94.13 ft/s
Explanation:
<u>Given:</u>
= time interval in which the rock hits the opponent = 10 s - 5 s = 5 s
= distance to be moved by the rock long the horizontal = 98 yards
= displacement to be moved by the rock during the time of flight along the vertical = 0 yard
<u>Assume:</u>
= magnitude of initial velocity of the rock
= angle of the initial velocity with the horizontal.
For the motion of the rock along the vertical during the time of flight, the rock has a constant acceleration in the vertically downward direction.

Now the rock has zero acceleration along the horizontal. This means it has a constant velocity along the horizontal during the time of flight.

On dividing equation (1) by (2), we have

Now, putting this value in equation (2), we have

Hence, the initial velocity of the rock must a magnitude of 94.13 ft/s to hit the opponent exactly at 98 yards.
Visible light is found between infrared rays (lower frequency, higher wavelength) and ultraviolet rays (higher frequency, lower wavelength). This the spectrum of light that we are able to see reflected back at us, and is also the spectrum of color that we are able to see.
Answer is D
Explanation:
It is given that,
= -40 mi/h,
= -40 mi/h
The negative sign indicates that x and y are decreasing.
We have to find
. Equation for the given variables according to the Pythagoras theorem is as follows.

Now, we will differentiate each side w.r.t 't' as follows.

or, 
So, when x = 4 mi, and y = 3 mi then z = 5 mi.
As, 
= 
= 
= 52
Thus, we can conclude that the cars are approaching at a rate of 52 mi/h.