Question

A motor car of 100 kW engine moves with a
uniform speed of 72 km/h. The forward
thrust applied by the engine on the car is :​

Answer 1

$\sf\large\underline\purple{Given:-}$

$\sf{\implies Power\:of\: motor\:car=100kw}$

$\sf{\implies Speed\:of\:the\:car=72km/h}$

$\sf\large\underline\purple{To\: Find:-}$

• The forward thrust applied by engine on the car=?

$\sf\large\underline\purple{Solution:-}$

• We know that 100kw=100000w and the uniform speed of car is given 72km/h but here we have to convert the speed of the car into m/s so, it comes 72km/h=20m/s by applying formula to calculate thrust applied by engine on car. Thrust is a force. When any vehicles pushes or accelerates mass in one direction, there is (force) just in the opposite direction. In physics, it is represented by Isaac Newton’s second and third laws. Force is used to represent how strongly an engine pushes. It can be used for many kinds of vehicles and engines such as car, motor bike, and truck engines.

$\sf\large\underline\purple{Formula\:used:-}$

$\sf{\implies Power=Force*Velocity}$

• Now calculate Force here first:-]

$\sf{\implies Here\:\:,P=100000w\:\:,V=20m/s}$

$\sf{\implies Force=\dfrac{Power}{velocity}}$

$\sf{\implies Force=\dfrac{100000}{20}}$

$\sf{\implies Force=5000N}$

$\sf\large{Hence,}$

• The forward thrust applied by engine on the car=5000N

Answer 2

Given

P=100kw

v=72km/h

here change both units

100kw=100000w

72km/h=72×5/18=20m/s

therefore,

• Force=P/v=100000/20=5000N