Answer:
7,79 seconds
Explanation:

You need to use the acceleration formula. A is acceliration,
is change in velocity and t is time.
You need to multiply the formula with t and divide by a and you get
a*t=
t=
/a
after that you just need to insert the numbers
change in velocity is 76.4 minus 0.
acceliration is gravitational acceleration which is 9.81.
After that you get
t=76.4/9.81
t= 7,787971458 s
According to the conservation of mechanical energy, the kinetic energy just before the ball strikes the ground is equal to the potential energy just before it fell.
Therefore, we can say KE = PE
We know that PE = m·g·h
Which means KE = m·g·h
We can solve for h:
h = KE / m·g
= 20 / (0.15 · 9.8)
= 13.6m
The correct answer is: the ball has fallen from a height of 13.6m.
Answer:
the ans is D... good luck
<h2>
Option A is the correct answer.</h2>
Explanation:
Acceleration due to gravity

G = 6.67 × 10⁻¹¹ m² kg⁻¹ s⁻²
Let mass of earth be M and radius of earth be r.
We have

Now
A hypothetical planet has a mass of one-half that of the earth and a radius of twice that of the earth.
Mass of hypothetical planet, M' = M/2
Radius of hypothetical planet, r' = 2r
Substituting

Option A is the correct answer.