Question

A car of mass 1000 kg starting from rest and moving with uniform acceleration covers a distance of 20 m is 2s. Calculate the work done by the engine of the car during this time.

Answer 1

given,
mass of the object=1000kg
initial velocity of the object=0m/s
distance traveled=20m
time taken=2sec
therefore work done ,
work= force* displacement.
work= force*20
force,
force= mass*acceleration
force= 1000*acceleration
acceleration,
s=ut+1/2at^2
20=0*2+1/2*a*(2)^2
20=0+1/2*a*4
20=2a
20/2=a
10=a
acceleration=10m/s^2
therefore,
force=mass*acceleration
F=1000*10
F=10000 N
therefore,
work done = force*displacement
W=10000*20
W=200000 J
W=2*10^5 J.
               i hope that this will help u.....................
 

Answer 2

Answer:200000 Nm

Explanation:

Mass = 1000kg

Initial velocity = 0m/s

Time = 2s

distance covered = 20 m

Work =?

= force x displacement

but force = ?

so, force = mass x acceleration

acceleration = ?

for that we use     s = ut + 1/2at².

20 = 0 x 2 + 1/2 x a x 2².

20 = 2a

a = 20/2 = 10

So, force = m x a

= 1000 x 10 = 10000 N

So,

work done = force x displacement

10000 x 20 = 200000 Nm

hence proved.