Answer:
5 hours
Explanation:
Let the required time be x hours. The time will be the same for both cars.
The cars will cover different distances because they are travelling at different speeds.
<em>D=S×T
</em>
The distance travelled by the slower car = 50×x miles.
The distance travelled by the faster car = 58×x miles.
The two distances differ by 40 miles.
58x−50x=40
8x=40
x=5 hours
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A second method:
The difference in the distances is 40 miles
The difference in the speeds is #8mph.
The time to make up the 40 miles= 
=5 hours
The tension in the string with friction would be the biggest because of the involvement of the force of gravity. This would result in that the friction force that is acting on the system. There is no friction in the frictionless system, and only the force of gravity is relevant.
It would be Joules.
Workdone is measured in Joules.
Workdone = Force * distance
Force = mass * acceleration
= kg * ms⁻²
= kgms⁻²
Distance = m
So, Force * distance
kgms⁻² * m
Apply laws of indices that says
x² * x³ = x²⁺³ = x⁵
Therefore, It would be kgm²s⁻²
m¹ * m¹ = m¹⁺¹ = m²
s⁻² is also = s / 2
