d.88 n
Explanation:
The force exerted by gravity on the mass is 88N;
Gravitational force is usually experienced by two bodies with masses.
This force causes all objects on earth to accelerate at 9.8m/s².
Force of gravity = mass x acceleration due to gravity
In this case, the force exerted on the object by gravity will be the weight of the object.
Weight is a force applied gravity on a body:
Weight of the masses = Force of gravity = mass x acceleration
Given mass = 9kg
Force of gravity = 9 x 9.8 = 88.2N approximately 88N
learn more:
Weight and mass brainly.com/question/5956881
#learnwithBrainly
(a) The maximum height reached by the ball from the ground level is 75.87m
(b) The time taken for the ball to return to the elevator floor is 2.21 s
<u>The given parameters include:</u>
- constant velocity of the elevator, u₁ = 10 m/s
- initial velocity of the ball, u₂ = 20 m/s
- height of the boy above the elevator floor, h₁ = 2 m
- height of the elevator above the ground, h₂ = 28 m
To calculate:
(a) the maximum height of the projectile
total initial velocity of the projectile = 10 m/s + 20 m/s = 30 m/s (since the elevator is ascending at a constant speed)
at maximum height the final velocity of the projectile (ball), v = 0
Apply the following kinematic equation to determine the maximum height of the projectile.

The maximum height reached by the ball from the ground level (h) = height of the elevator from the ground level + height of he boy above the elevator + maximum height reached by elevator from the point of projection
h = h₁ + h₂ + h₃
h = 28 m + 2 m + 45.87 m
h = 75.87 m
(b) The time taken for the ball to return to the elevator floor
Final height of the ball above the elevator floor = 2 m + 45.87 m = 47.87 m
Apply the following kinematic equation to determine the time to return to the elevator floor.

To learn more about projectile calculations please visit: brainly.com/question/14083704
A. freezing, when water turns to ice the water is turning from a liquid to a solid.