Question

A 20 kg object is dropped from a very tall building. What is the weight of this objects? After 5 seconds, how has the object fallen and what is its speed at this instant?

Answer 1

1. What is the weight of this objects?

Weight is simply the product of mass and gravitational acceleration. Therefore the weight is:

w = 20 kg * 9.81 m/s^2

w = 196.2 kg m/s^2 = 196.2 N

 

2. After 5 seconds, how has the object fallen and what is its speed at this instant?

We can use the formula:

y = v0 t  + 0.5 g t^2

v = v0 + g t

where v0 = 0 since the object starts from rest, y is the distance it fell, t is time

y = 0 + 0.5 * 9.81 * 5^2 = 122.625 m

v = 0 + 9.81 * 5 = 49.05 m/s