if it requires 25 kilowatt to drive an automobile at 36 km per hour along a level road what is the frictional force opposing the motion
Answers
Power required = 25 kilowatt
Velocity of automobile = 36 km/hr
10 m/s
Frictional force exerted by road.
The work done by an object per unit time is known as power.
But ,
Work :- When a Force displace a body in direction of force then It is known as work done by force.
- Put the value of W.
Frictional force exerted by road f.
- Power required = 25 Kilo watt.
- Speed of the automobile = 36 Km/h.
- Frictional force = f.
Let's see the definition of Power,
Power is defined as rate of doing work.
Its units are:-
- S.I units = Watt.
- C.G.S units = erg/second.
- Commercial unit :- KWH.[Kilowatt hour]
Its Formula is given by:-
Here ,
- P denotes Power,
- W denotes Work done.
- t denotes Time period.
For, Instantaneous Power,
[Taking over a short interval of time]
Now,
W = F.S
Substituting it,
As Force is constant it cannot be differentiated.
As we know,
Substituting it,
Now, From the question,
Velocity is given in Km/hr, it needs to be converted to m/s.
Therefore,
Therefore, Speed will be,
Now,
Applying the formula of instantaneous Power.
Substituting the values,
Now,
So, the Frictional force opposing the motion is 2,500 N.