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

Answer:

option (b) is correct.

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

Answer:

New potential energy will be 784 J

So option (b) will be correct answer

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 $980=m\times 9.8\times 10$

m = 10 kg

Now new height h = 8 m

So new potential energy $E=mgh=10\times 9.8\times 8=784J$

So option (B) will be the correct answer