Physics 2002 JAMB Past Questions - Question 9: A body weighing 80N stands in an elevator that is about to move. The force exerted by the floor on the body as the elevator moves upwards with an acceleration of 5ms-² is

Correct Answer

D

Explanation

To find the force exerted by the floor on the body in an elevator moving upwards with an acceleration of 5 m/s², you can use Newton's second law of motion, which states that the net force on an object is equal to the mass of the object times its acceleration:

F = m * a

Where:
F is the net force (the force exerted by the floor in this case).
m is the mass of the body.
a is the acceleration.

First, you need to find the mass of the body using the weight (force due to gravity):

Weight (W) = 80 N
Acceleration due to gravity (g) ≈ 9.81 m/s² (approximately)

W = m * g

Solving for m:

m = W / g
m = 80 N / 9.81 m/s² ≈ 8.16 kg

Now that you have the mass, you can find the net force (the force exerted by the floor) as the elevator moves upwards with an acceleration of 5 m/s²:

F = m * a
F = 8.16 kg * 5 m/s²
F = 40.8 N

So, the force exerted by the floor on the body as the elevator moves upwards with an acceleration of 5 m/s² is approximately 40.8 Newtons.