Discuss whether any work is being done by each of the following agents and, if so, whether the work is positive or negative: (a) a chicken scratching the ground, (b) a person studying, (c) a crane lifting a bucket of concrete, (d) the gravitational force on the bucket in part (c), and (e) the leg muscles of a person in the act of sitting down.

Write the work done in each of the following cases as zero positive or negative. (a)Work done by centripetal force in circular motion. (b)Work done by friction. (c)Work done by gravitational force on a freely falling object. (d)Work done by the applied force in lifting an object.

The sign of work done by a force is important to understant. State carefully if the following quantities are positive or negative. (a) Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket. (b) Work done by the gravitational force in the above case. (c ) Work done by friction on a body sliding down an inclined plane. (d) Work done by an applied froce on a body moving on a rough horizontal plane with uniform velocity. (e ) Work done by the resistive force of air on a vibrating pendulum in bringing it to rest.

The sign of work done by a force is important to understant. State carefully if the following quantities are positive or negative. (a) Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket. (b) Work done by the gravitational force in the above case. (c ) Work done by friction on a body sliding down an inclined plane. (d) Work done by an applied froce on a body moving on a rough horizontal plane with uniform velocity. (e ) Work done by the resistive force of air on a vibrating pendulum in bringing it to rest.

The sign of work done by a force on a body is important to understand .State carefully if the following quantities are positive or negative : (a) work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket . (b) work done by gravitational force in the above case , (c ) work done by friction on a body siding down an inclined plane , (d ) workdone by an applied force on a body moving on a rough horizontal plane woth uniform velocity . (d) work done by the resistive force of air on a vibrating pendulum in bringing it to rest .

The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative : Work done by gravitational force in lifting a bucket out of a well by means of a rope tied to the bucket

Four particles A,B, C and D each of mass m are kept at the corners of a square of side L. Now the particle D is taken to infinity by an external agent keeping the other particles fixed at their respective positions . The work done by the gravitational force acting on the particle D During its movement is