Answer:
Explanation:
When a lightning bolt travels from the cloud to the ground it actually opens up a little hole in the air, called a channel. Once then light is gone the air collapses back in and creates a sound wave that we hear as thunder. The reason we see lightning before we hear thunder is because light travels faster than sound!
It must be either speeding up, or slowing down, or turning. There are no other possibilities.
Answer:
a) 
b) This value of specific heat is close to the specific heat of ice at -40° C and the specific heat of peat (a variety of coal).
c) The material is peat, possibly.
d) The material cannot be ice because ice doesn't exists at a temperature of 100°C.
Explanation:
Given:
- mass of aluminium,

- mass of water,

- initial temperature of the system,

- mass of copper block,

- temperature of copper block,

- mass of the other block,

- temperature of the other block,

- final equilibrium temperature,

We have,
specific heat of aluminium, 
specific heat of copper, 
specific heat of water, 
Using the heat energy conservation equation.
The heat absorbed by the system of the calorie-meter to reach the final temperature.



The heat released by the blocks when dipped into water:

where
specific heat of the unknown material
For the conservation of energy : 
so,


b)
This value of specific heat is close to the specific heat of ice at -40° C and the specific heat of peat (a variety of coal).
c)
The material is peat, possibly.
d)
The material cannot be ice because ice doesn't exists at a temperature of 100°C.
Answer:
715 N
Explanation:
Since the system is moving at a constant velocity, the net force must be 0. The tension on the road is equal and opposite direction with the kinetic friction force created by the road and the stuntman.
Let g = 9.8 m/s2
Gravity and equalized normal force is:
N = P = mg = 107*9.8 = 1048.6 N
Kinetic friction force and equalized tension force on the rope is
