Answer: -39.2 m/s or 39.2 m/s directed downwards
Explanation:
This situation is a good example of Free Fall, where the main condition is that the initial velocity must be zero
, and the acceleration is constant (acceleration due gravity).
So, in order to calculate the final velocity
of the rock just at the moment it hitsthe bottom of the cliff, we will use the following equation:

Where:
is the acceleration due gravity (directed downwards)
is the time it takes to the rock to fall down the cliff

This is the rock's final velocity and its negative sign indicates it is directed downwards
Answer:
16 cm
Explanation:
For protons:
Energy, E = 300 keV
radius of orbit, r1 = 16 cm
the relation for the energy and velocity is given by

So,
.... (1)
Now,

Substitute the value of v from equation (1), we get

Let the radius of the alpha particle is r2.
For proton
So,
... (2)
Where, m1 is the mass of proton, q1 is the charge of proton
For alpha particle
So,
... (3)
Where, m2 is the mass of alpha particle, q2 is the charge of alpha particle
Divide equation (2) by equation (3), we get

q1 = q
q2 = 2q
m1 = m
m2 = 4m
By substituting the values

So, r2 = r1 = 16 cm
Thus, the radius of the alpha particle is 16 cm.
The correct is D.
Explanation: The specific heat is defined as heat required to raise the temperature of a unit mass by one degree. Greater the specific heat, more is the heat required to raise the temperature for equal mass. So, the temperature of the material with lowest specific heat will increase the most for the same amount of heat energy.
D. 128.25 because force=mass x acceleration