A . Thermal
Thermal Energy, or heat, is the internal energy in substance the vibration & movement of the atoms & molecules within substances. Geothermal energy is an example of thermal energy.
<span><span>D.</span><span>Measurements are taken in a way that is the same every time.- apex
</span></span>
Answer:
Solution
verified
Verified by Toppr
Given:
Mass of body = 30 kg
gravitational acceleration on the moon = 1.62 m/s
2
Weight of the body on the moon = Mass of the body×gravitational acceleration on the moon=30×1.62=48 N
Answer:
(a) 
(b) 
(c) K.E. = 21.168 J
(d) 
Explanation:
Given:
- mass of a block, M = 3.6 kg
- initial velocity of the block,

- constant downward acceleration,

That a constant upward acceleration of
is applied in the presence of gravity.
∴
- height through which the block falls, d = 4.2 m
(a)
Force by the cord on the block,



∴Work by the cord on the block,


We take -ve sign because the direction of force and the displacement are opposite to each other.

(b)
Force on the block due to gravity:

∵the gravity is naturally a constant and we cannot change it


∴Work by the gravity on the block,



(c)
Kinetic energy of the block will be equal to the net work done i.e. sum of the two works.
mathematically:


K.E. = 21.168 J
(d)
From the equation of motion:

putting the respective values:

is the speed when the block has fallen 4.2 meters.