Home
Class 11
PHYSICS
According to work energy theorem or work...

According to work energy theorem or work energy principle, work done by net force in displacing a body is always equal to change in K.E. of the body. Similarly , if some work is drawn from the body, K.E. of the body decreases by the same amount. In either process, we assume that potential energy of the body does not change.
Read the above passage and answer the following question:
(i) A car weighing 500 kg is running at a speed of `72 km//h`. In how much distance will it stope by applying a braking force of 4000N?
(ii) What are the implication of this theorem in day to day life ?

Text Solution

Verified by Experts

(i) Here, `m=500kg, u=72km//h=(72xx1000)/(60xx60)m//s=20m//s`
`s=?, upsilon=0, F=-4000N`
As work done `=` change in K.E. of the car,
`:. Fxxs=(1)/(2)m(upsilon^(2)-u^(2))`
`-4000xxs=(1)/(2)xx500(0-20^(2))=-250xx400`
`s=(-250xx400)/(-4000)=25m`
(ii) In day to day life, K.E. acquired corresponds to output and workk done corresponds to work put in through out efforts. The theorem implies that under ideal conditions, our achievement `//` output will be equal to work put in by us. We should plug all loop holes involving loss of energy to get the maximum output.
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • WORK, ENERGY AND POWER

    PRADEEP|Exercise Multiple choice question|29 Videos
  • WORK, ENERGY AND POWER

    PRADEEP|Exercise Fill in the blanks|10 Videos
  • WORK, ENERGY AND POWER

    PRADEEP|Exercise higher order thinking skills|10 Videos
  • THERMODYNAMICS

    PRADEEP|Exercise Assertion- Reason Type Questions|19 Videos

Similar Questions

Explore conceptually related problems

According to work energy principle, work done by …………………..in displacing body …………………to…………………… in………………. .

According to the work energy theorem, the work done by the net force on a particle is equal to the change in its

Knowledge Check

  • Work done by a force in displacing a body is an example of

    A
    vector product
    B
    scalar product
    C
    addition of vectors
    D
    division of vectors
  • The work done by kinetic friction on a body :

    A
    is always negative
    B
    is always zero
    C
    may be `+ve,-ve` or zero
    D
    is always positive
  • According to work-energy theorem, the work done by the net force on a particle is equal to the change in its

    A
    kinetic energy
    B
    potential energy
    C
    linear momentum
    D
    angular momentum
  • Similar Questions

    Explore conceptually related problems

    When a conservative force does positive work on a body, the potential energy of the body

    Work is always done on a body when

    In the above problem, minimum work is done when the body is

    Work done upon a body is

    The work done by a body against friction always results in