What will be the energy possessed by a stationary object of mass 10 kg placed at a height of 20 m above the ground? (take g = 10 m/s2)

A : 2 J
B : 20 kJ
C : 200 J
D : 2 kJ
General Science
Physics
Work Power Energy
Answer
Option 4 : 2 kJ
Explanation

The correct answer is 2 kJ.

CONCEPT:

  • Potential energy: The energy of any object due to its position with respect to a reference point is called potential energy. It is denoted by PE.

Potential energy is given by:

PE = m g h.

Here, PE is the Potential Energy, m is the mass, g is the acceleration due to gravity, and h is the height at which the object is placed

CALCULATION:

Given that: 

Mass (m) = 10 Kg

Height (h) = 20 m

P.E. = 10 x 10 x 20

P.E.= 2000 J

 P.E. = 2 kJ

  • Kinetic energy: The energy due to the motion of the object is called kinetic energy. 
    • Kinetic energy (KE) = 1/2 (mv2)
    • Where m is mass and v is velocity. 
  • Since the object is stationary (at rest) so the velocity is zero. Hence the kinetic energy of the object will be zero.
  • Only the potential energy of the object will be there at the height.