Answer:
F = 3600 [N]
Explanation:
To solve this problem we must use Newton's second law, which tells us that the sum of force must be equal to the product of mass by acceleration.
ΣF = m*a
where:
F = force [N]
m = mass = 2000 [kg]
a = acceleration = 1.8 [m/s^2]
Now replacing:
F = 2000*1.8
F = 3600 [N]
Answer:

Explanation:
We are given that three resistors R1, R2 and R3 are connected in series.
Let
Potential difference across 
Potential difference across 
Potential difference across 
We know that in series combination
Potential difference ,
Using the formula

Hence, this is required expression for potential difference.
Time period of fan (t) = 1 / 2 = 0.5 seconds
Angular velocity (ω)= 2π/t
ω = 4π
v = ωr
v = 4π x 0.61
v = 7.66 m/s