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प्रश्न
The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:
Work done by gravitational force on a man in lifting a bucket out of a well by means of a rope tied to the bucket.
उत्तर
The work done by gravitational force on a man lifting a bucket out of a well by means of a rope tied to the bucket is negative. This results from the bucket moving upward, opposite to the gravitational force, which acts downward. Since the direction of the gravitational force and the displacement of the bucket form an angle of 180°, the work done is calculated as:
`W = F.dcosθ = F.dcos180° = −Fd`, making it negative.
संबंधित प्रश्न
A body of mass 2 kg initially at rest moves under the action of an applied horizontal force of 7 N on a table with coefficient of kinetic friction = 0.1. Compute the
- Work done by the applied force in 10 s
- Work done by friction in 10 s
- Work done by the net force on the body in 10 s
- Change in kinetic energy of the body in 10 s and interpret your results.
Can the work by kinetic friction on an object be positive? Zero?
Can static friction do nonzero work on an object? If yes, give an example. If no, give reason.
Can normal force do nonzero work on an object? If yes, give an example. If no, give reason.
Two springs A and B(kA = 2kB) are stretched by applying forces of equal magnitudes a the four ends. If the energy stored in A is E, that in B isA
Calculate the work done by a car against gravity in moving along a straight horizontal road. The mass of the car is 400 kg and the distance moved is 2 m.
A particle of mass 500 gm is moving in a straight line with velocity v = bx5/2. The work done by the net force during its displacement from x = 0 to x = 4 m is : (Take b = 0.25 m-3/2 s-1).
A potential barrier of 0.4 V exists across a p-n junction. An electron enters the junction from the n-side with a speed of 6.0 × 105 ms-1. The speed with which the electron enters the p side will be `x/3 xx 10^5 "ms"^-1`, and the value of x is ______.
(Given the mass of electron = 9 × 10-31 kg, the charge on electron = 1.6 × 10-19 C.)
The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:
Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket.
The sign of work done by a force on a body is important to understand. State carefully if the following quantity is positive or negative:
Work done by friction on a body sliding down an inclined plane.
