Answer:
0.0321 g
Explanation:
Let helium specific heat 
Assuming no energy is lost in the process, by the law of energy conservation we can state that the 20J work done is from the heat transfer to heat it up from 273K to 393K, which is a difference of ΔT = 393 - 273 = 120 K. We have the following heat transfer equation:

where
is the mass of helium, which we are looking for:

All of them have the same potential energy <span />
Answer:
Answer is C
Explanation:
Let's say the pendulum starts swinging from its max height from the left. It then will go down and reach the equilibrium position, this will make it lose GPE while gaining KE (the loss in GPE = gain in KE). At the equilibrium position it has the max KE (max velocity) and minimum GPE. After passing the equilibrium it then starts to head up to the max height on the right, the pendulum gains GPE while losing KE and at the top will have minimum KE while having max GPE. Meaning throughout its joruney the total energy remains constant as
Total energy = KE + GPE
I have attached a simple diagram below, the y axis is the energy and x axis being the time (where t = 0 is the pendulum starting from max height left of the equilibrium). The green curve the the GPE and blue curve is KE. Red line shows that at all times the energy is constant.
Gravity is one of the significant forces of the universe. It is the force that draws other objects closer to the center of another object. The bigger the object, the higher its force of gravity and nearby objects are accelerated towards the big mass.
It is this force of gravity that keeps the planets in the solar system orbiting around the sun. The suns gravitational pull is stronger than those of the planets hence pulls the planets on their orbits around the star. Gravity also played a part in the formation of the planets. Gravity caused the condensation of dust and rocks into a mass that continually attracted more matter as it gained mass (due to gaining more associated gravitational pull).
Each point in the chain supports the weight of all the mass below it.
At the bottom end of the chain, the weight is (175 x 9.8) = 1,715 N .
At the top of the chain, the weight is (175 + 12) x (9.8) = 1,833 N .
The tension in the chain varies linearly from 1,715N at the bottom
to 1,833N at the top.