Question

A mass resting on a shelf 10.0 meters above the floor has a gravitational potential energy of 980. joules with respect to the floor. The mass is moved to a shelf 8.00 meters above the floor. What is the new gravitational potential energy of the mass?

a. 960. J
b. 784 J
c. 490. J
d. 196 J

Answer 1

option (b) is correct.

Step-by-step explanation:

h1 = 10 m

U 1 = 980 J

Let mg be weight of mass.

U1 = m x g x h1

980 = mg x 10

mg = 98

Now h = 8 m

U2 = mg x h = 98 x 8

U2 = 784 J

thus, the potential energy is 784 J.

Answer 2

New potential energy will be 784 J

So option (b) will be correct answer

Step-by-step explanation:

We have given height of the shelf h = 10 m

Potential energy E = 980 J

Acceleration due to gravity
`g=9.8m/sec^2`

We know that potential energy
`E=mgh`

So
`980=m* 9.8* 10`

m = 10 kg

Now new height h = 8 m

So new potential energy
`E=mgh=10* 9.8* 8=784J`

So option (B) will be the correct answer