Question

A 2 kg object is released from rest from a height of 3 m above Earth's surface. How much kinetic energy does the object have when it reaches a height of 1 m? (A) 2.5 J (B) 10 J (C) 20 J (D) 30 J (E) 40 JFigure:A 2kg object is hanging

Answer 1

Answer:

Kinetic energy, E = 40 Joules

Explanation:

Given that,

Mass of the object, m = 2 kg

It is released from rest from a height of 3 m above Earth's surface, $h_1=3\ m$

We need to find the kinetic energy the object have when it reaches a height of 1 m, $h_2=1\ m$

It is a case of conservation of mechanical energy. It states that the total energy of the system remains constant. The kinetic energy is given by :

$E=mg(h_1-h_2)$

$E=2\times 10\times (3-1)$

E = 40 Joules

So, the kinetic energy of the object when it reaches a height of 1 m is 40 joules. Hence, this is the required solution.