The graph between the resistive force F acting on a body and the distance covered by the body is shown in the figure. The mass of the body is 25kg and initial velocity is 2m/s. When the distance covered by the body is 4m, its kinetic energy (in Joule) would be :
Area under curve
W = work done by resistive force F
The correct answer is: 10
A particle moves with a velocity under the influence of a constant force The instantaneous power (in Js–1) applied to the particle is :
The correct answer is: 140
An electric motor creates a tension of 4500N in hoisting cable and reels it at the rate of 2m/s. What is the power of electric motor in kW?
The correct answer is: 9
A body of mass 5kg is acted upon by a variable force. The force varies with the distance covered by the body. Find the kinetic energy (in Joule) of the body when the body has covered 30m distance? Assume that the body starts from rest.
Work done by force when body has covered 25m
Area under curve upto distance 25m
Area between 25m to 30m is
So total work done by variable force till 30m is 250+45 = 295Joule
So, change in kinetic energy = 295J.
So final energy = 295J.
The correct answer is: 295
In the figure shown initially spring is in unstretched state and blocks are at rest. Now 100N force is applied on block A and B as shown in figure. After some time velocity of A becomes 2m/s and that of B 4m/s and block A displaced by amount 10cm and spring is stretched by amount 30cm. Then work done by spring force on A will be (in Joule) :
The correct answer is: -6
The potential energy for a force field is given by U(x,y) = sin(x + y). The force acting on the particle of mass m at
The correct answer is: 1
A spring of force constant 800N/m has an extension of 5cm. The work done (in Joule) in extending it from 5cm to 15cm is :
The correct answer is: 8
The work done by the force where A is a constant and x and y in meters around the path shown is :
Take, A = 50N/m and d = 2.
The correct answer is: 400
An object is moving along a straight line path from P to Q under the action of a force If the co-ordinate of P and Q in metres are (3, 2, –1) and (2,-1,4) respectively. Then the work done by the force in Joule is :
The correct answer is: 15
Power supplied to a particle of mass 2kg varies with time as P = watt. Here t is time in second. If velocity of particle at t =0sec is v = 0m/s. The velocity of particle (in ms-1) at time t = 2sec will be :
Applying work energy theorem
Solving we get v = 2 m/s
The correct answer is: 2