Question

An object of weight 120 N is at a certain height
above the ground. If the potential energy of
the object is 480 J, the height at which the
object is with respect to the ground will be
(a) 0.25 m
(b) 4 m
(C) 0.4 m
(d) 25 m​

Answer 1

Given :

Weight of object = 120N

Potential energy at a certain height = 480J

To Find :

Height of object from the ground.

Solution :

■ The energy possessed by a body by virtue of its position relative to others is called potential energy.

• It is a scalar quantity having only magnitude.
• It can't be negative or zero.
• It is a relative quantity$.$
• At reference point it is taken as zero (i.e., at ground)

Potential energy of body of mass at a height h from ground is given by : [U = mgH]

ATQ, weight of body = mg = 120

By substituting the given values;

➠ U = mg × H

➠ 480 = 120 × H

➠ H = 480/120

➠ H = 4 m

∴ (B) is the correct answer!