A car weighing 9800 N is moving with a speed of 40 km/h.<br />
On the application of the brakes It comes to rest after travel-<br />
ling a distance of 50 metres. Calculate the average retarding<br />
force.<br />
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A car weighing 9800 n is moving with a speed of 40 km/h. On the application of the brakes, it comes to a rest after traveling a distance of 50 meters. What is the average retarding force?
4 Answers
John Barrow, former Taught Physics at UK Secondary School (1982-2010)
Answered October 26, 2019 · Author has 141 answers and 25.5K answer views
Conservation of energy allows you to work out the decelerating force. It is assumed that no other forces - like mechanical friction in the car’s bearings or air resistance - are involved to complicate matters.
Parameters involved are …
s - the braking distance to bring the car to rest
u - the initial speed at the time braking starts
v - the fnal speed which of course is zero
m - the mass of the vehicle
m = 9800 / 10 kg (where the acceleration due to gravity is taken as 10 ms^-2).
So, m = 980 kg.
The initial speed, u, is 40 kmh^-1 which is 11.11 ms^-1
The dissipation of the car’s kinetic energy in the b
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Other Answers
Sean Vargas, B.S. Physics & Mechanical Engineering
Answered December 27, 2019
9800N= 980kg =m*(g/g) g=10
Vo= 40kph = 40000/3600 = 11.11 m/s
Vf=0
d= 50m
a= acceleration=> negative acceleration= Deceleration=> retarding force=??
F=ma
Vo^2-Vf^2= 2a*d
(11.11^2)/(2*50)= a
F=[(11.11^2)/100]*980 = 1209.63N