Advertisements
Advertisements
प्रश्न
Explain briefly why the work done by a fielder when he takes a catch in a cricket match is negative.
Advertisements
उत्तर
The work done by a fielder when he takes a catch in a cricket match is negative because the force applied by the fielder is in the direction opposite to the displacement of the ball. The angle between the force applied and the displacement of the ball is 180. We know that work done = F.s cosΘ
Therefore, work done = −F.s
APPEARS IN
संबंधित प्रश्न
State the SI unit of work.
Give two examples of couple action in our daily life.
State the conditions of equilibrium for a rigid body.
Give two examples of work done.
A machine raises a load of 750 N through a height of 16 m in 5s. calculate:
(i) work done by machine,
(ii) power at which the machine works.
State larger units of power.
A truck driver can load oil drums into the back of the truck by pushing them up a sloping plank, or by lifting them directly. Each drum has a mass of 80 kg, the plank is 3 m long, and the back of the truck is 0.8 m above the ground.
(i) How much force would be needed to lift a drum into the truck directly/without using the plank? (Take g = 10 m/s2)
(ii) How much energy would be required in lifting the drum into the truck without the plank?
(iii) If the force needed to push the drum up the plank is 300 N, why is this less than the answer to part (i)?
(iv) When the truck is loaded, the driver drives off. List the major energy changes that take place in moving the truck.
(v) The driver has to stop at the factory gates. What happens to the kinetic energy of the truck?
A force is applied on a body of mass 20 kg moving with a velocity of 40 ms−1. The body attains a velocity of 50 ms−1 in 2 seconds. Calculate the work done by the body.
