Technically, I can't answer the question, because you won't
let me see the picture that goes along with it and is a part of it.
But I'm familiar with the set-up, have dealt with the question before,
and I can answer it from my previous experience and general knowledge.
If there is 500g of mass inside the jar when you lower it over
the candle, then there will be 500g of mass at any time after that,
forever, or until you pick up the jar and take some mass out or put
some more in. It doesn't matter how long you wait. It also doesn't
matter whether or not the candle is burning, whether or not the sun
is shining on the jar, or whether somebody comes along and spray-paints
the outside of the jar with black paint. Matter is not created or destroyed.
Whatever mass was inside when the jar got closed stays in there.
Explanation:
Natural length of a spring is 
. The spring is streched by 
. The resultant energy of the spring is 
.
The potential energy of an ideal spring with spring constant 
and elongation 
is given by 
.
So, in the current problem, the natural length of the spring is not required to find the spring constant .
∴ The spring constant of the spring = 
Answer: D. All of the choices
Explanation:
Number 29
= 10 N (from rocket) + 10 N (from wheels) - 7 N (from parachute 'cause force in other direction)
= 20 N - 7 N
= 13 N ✔
Number 30
= 100 N - 85 N
= 15 N to the left ✔
Answer:
The correct option is;
B) The specific heat of ice is less than that of water.
Explanation:
Here we have
Let the amount of energy added to the ice at -10 C to raise the temperature to -5 C be X J
Let the amount of energy added to the water at 15 C to raise the temperature to 20 C be Y J
We know that the heat required, ΔQ to raise the temperature of a substance is given by
ΔQ = m·c·Δθ
Where:
m = Mass of the substance
c = Specific heat capacity
Δθ = Temperature change
Since the mass of the ice and the water are the same, so also is the change in temperature, (-5 - (-10) = 5 and 20 - 15 = 5) we have
for m₂·c₂·Δθ₂ > m₁·c₁·Δθ₁
Where:
m₁, c₁, Δθ₁, is for the ice and m₂, c₂, Δθ₂ is for the water and
m₁ = m₂
Δθ₁ = Δθ₂
Therefore,
c₂ > c₁ = c₁ < c₂
That is the specific heat capacity of the ice is lesser than the specific heat capacity of the water.
