Answer:
1.2 m from the left end
Explanation:
= mass of the person = 90 kg
= mass of friend = 60 kg
= distance of pivot from the person or from the left end
= length of the seesaw board = 3.0 m
= distance of pivot from the friend or from right end = L - r = 3 - r
Using equilibrium of torque about the pivot

True a change in temperature can cause a change in density.
Answer:
a) 
b) 
Explanation:
Given:
- mass of copper,

- initial temperature of copper,

- specific heat capacity of copper,

- mass of water,

- initial temperature of water,

- specific heat capacity of water,

a)
<u>∵No heat is lost in the environment and the heat is transferred only between the two bodies:</u>
Heat rejected by the copper = heat absorbed by the water


b)
<u>Now the amount of heat transfer:</u>



∴Entropy change


