Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?
Solution and Explanation
Initial velocity of the car \(u =\) \(60 \ km/h\)
\(u = \frac {60×1000}{60×60}\)
\(u= \frac {50}{3}\ ms^{-1}\)
Final velocity \(v = 0\) (object has to be stopped)
Initial kinetic energy \(= \frac 12×m×v^2\)
\(KE=\frac 12×1500×(\frac {50}{3})^2\)
\(KE = \frac {1500 \times 2500 \ }{2 \times 9}\)
\(KE= 208333.30\ J\)
Final kinetic energy \(= \frac 12×1500×0 = 0\)
Therefore,
Work done = change in kinetic energy = \(208333.30-0 = 208333.30\ J\)
Top CBSE Class IX Questions
- The following table gives the lifetimes of 400 neon lamps:
Length (in hours)
Number of lamps
300 − 400
14
400 − 500
56
500 − 600
60
600 − 700
86
700 − 800
74
800 − 900
62
900 − 1000
48
(i) Represent the given information with the help of a histogram.
(ii) How many lamps have a lifetime of more than 700 hours? - Give an example to show that even as a young girl Santosh was not ready to accept anything unreasonable.
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- What do you think Dinamani is the name of? Give a reason for your answer.
Why was Santosh sent to the local school?
Concepts Used:
Work
Work is the product of the component of the force in the direction of the displacement and the magnitude of this displacement.
Work Formula:
W = Force × Distance
Where,
Work (W) is equal to the force (f) time the distance.
Work Equations:
W = F d Cos θ
Where,
W = Amount of work, F = Vector of force, D = Magnitude of displacement, and θ = Angle between the vector of force and vector of displacement.
Unit of Work:
The SI unit for the work is the joule (J), and it is defined as the work done by a force of 1 Newton in moving an object for a distance of one unit meter in the direction of the force.
Work formula is used to measure the amount of work done, force, or displacement in any maths or real-life problem. It is written as in Newton meter or Nm.