An object is dropped from 42m tall building. how long does it take to reach the ground?

It takes 2.93 s for the object to reach ground from the height of 42 m.

Explanation:

Given:

Displacement of the object is,

As it is dropped, initial velocity of the object is,

Acceleration of the object is equal to acceleration due to gravity and is equal to,

Now, using Newton's equation of motion and plugging in the values, we get:

So, it takes 2.93 s for the object to reach ground from the height of 42 m.

conduction, convection, radiation

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg