Question

An object of mass 1.5 kg rests on a shelf where it has a gravitational potential energy of 7 joules. An object of mass 4.5 kg is placed on the same shelf. What is the gravitational potential energy of this second object? A. 7 joules B. 10 joules C. 21 joules D. 31.5 joules

Answer 1

Answer:

C. 21 Joules

Explanation:

We apply the formula to calculate the potential energy (Ep):

Ep=m*g*h

Where:

Ep : potential energy in Joules (J)

m :mass in kilograms (kg)

g  acceleration due to gravity  (m/s²)

h: height in meters (m)

Calculation of the height (h)

Ep = m*g*h

7 = (1.5 )*(9.8) *(h )

7 = (14.7) (h )

h = 7 /  (14.7)

h= 0.476 m

Gravitational potential energy of the second object

Ep = m*g*h

Ep = (4.5 )*(9.8) *(0.476 )

Ep = (4.5 )*(9.8) *(0.476 )

Ep = 21 J