The nail has become a temporary magnet, while the
bar magnet remains a permanent magnet.
Answer:
E = 169.34 J
Explanation:
First, we need to find the frictional force between the back tire and the road. For that purpose, we use the following formula:
f = μR = μW
f = μmg
where,
f = frictional force = ?
μ = coefficient of friction between tire and road = 0.8
g = 9.8 m/s²
m = mass supported by back tire = (0.5)(90 kg) = 45 kg
Therefore,
f = (0.8)(45 kg)(9.8 m/s²)
f = 352.8 N
Now, for the heat energy we use the formula of work. Because, thermal energy will be equal to work done by frictional force:
E = W = fd
where,
E = Thermal Energy = ?
f = frictional force = 352.8 N
d = displacement = 48 cm = 0.48 m
Therefore,
E = (352.8 N)(0.48 m)
<u>E = 169.34 J</u>
