Advertisements
Advertisements
प्रश्न
Advertisements
उत्तर
APPEARS IN
संबंधित प्रश्न
Work done = Force × ........................................
The S.I. unit of work is
How much work is done when a body of mass m is raised to a height h above the ground?
The work done on an object does not depend on the :
A cricket ball is thrown up from the earth's surface. What happens to its P.E.
(a) during the motion
(b) at the highest point?
Fill in the boxe to show the corresponding energy transformation.
Give an example
Chemical energy changes to heat energy.
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 coolie is pushing a box weighing 1500 N up an inclined plane 7.5 m long on to a platform, 2.5 m above the ground.
(i) Calculate the mechanical advantage of the inclined plane. (ii) Calculate the effort applied by the coolie.
(iii) In actual practice, the coolie needs to apply more effort than what is calculated. Give one reason why you think the coolie needs to apply more effort.
