Question

You hold a metal block of mass 40 kg above your head at a height of 2 m.
How much work is done by gravity if you let the block fall to the ground?
O A. -80 j
O B. 80
O C. 784 J
O D. -784

Answer 1

Answer:

The work done by gravity is 784 J.

Explanation:

Given:

Mass of the block is, $m=40\ kg$

Height to which it is raised is, $h=2\ m$

Acceleration due to gravity is, $g=9.8\ m/s^2$

Now, work done by gravity is equal to the product of force of gravity and the distance moved in the direction of gravity. So,

$\textrm{Work by gravity}=F_g\times h$

Force of gravity is given as the product of mass and acceleration due to gravity.

$\therefore F_g=mg=40\times 9.8=392\ N$. Now,

$\textrm{Work by gravity}=F_g\times h=392\times 2=784\ J$

Therefore, the work done by gravity is 784 J.

Answer 2

Answer:

C. 784 J

Explanation:

Just got it right :)