Explanation:
Given that,
Rate of cooling of air
Initial temperature= 80°C
Final temperature = 5°C
We need to calculate
Using newton's law of cooling
Where, 
Here, 
= 25°C (surrounding temperature)
dt = 1 minute
Put the value into the formula
Hence, This is the required answer.
The average power output is the ratio between the work done to compress the spring, W, and the time taken, t:
(1)
The work done is equal to the elastic energy stored by the compressed spring:
where
is the spring constant and
is the compression of the spring. If we substitute the numbers, we find:
And now we can use eq.(1) to calculate the average power output:
Answer:
Explanation:
Given that,
Magnetic force acting on an electron, 
The magnitude of the magnetic field,
We need to find the magnitude of the velocity. We know that the magnetic force is given by :
Where
v is the velocity
So,
So, the magnitude of velocity is
.
