Work Power and Energy

• Very Important Multiple Choice Questions (MCQs) with Answers of the Chapter No.7: Work Power and Energy in Physics Class 11 Sindh Book Boards.
• Definition of Work and Mathematical Definition of Work
• Dimension and Nature of Work
• Units of Work
• Definition of power
• Definition of average power with its mathematical form
• Dimension and nature of power units of power
• Definition of a conservative field with example
• State and Explain Gravitational Field as a conservative field
• Definition of energy and dimension of and nature of energy units of energy
• Definition of potential energy with formula and derivation
• Definition of kinetic energy with formula and derivation
• State and explain law of conservation of energy
• Derivation of internal conservation of potential energy and kinetic energy (work energy equation)
• Definition of absolute gravitational potential energy
• Various sources of energy: (i) Wind Energy (Wind Power) (ii)   Hydro electricity (Water Power) (iii)  Fossil Fuel (iv)  Nuclear Energy (v) Geothermal Energy (vi)  Solar Energy
• Calculate the work done by a force F specified by F = 3i + 4j + 5k in displacing a body from position B to position A along a straight path. The position vectors A & B are respectively given as rA = 2i + 5j – 2k & rB = 7i + 3j – 5k
• A 2000 kg car traveling at 20 m/s comes to rest on a level ground in a distance of 100 m. How large is the average frictional force tending to stop it?
• A 100-kg man is in a car traveling at 20 m/s. (a) Find his kinetic energy. (b) The car strikes a concrete wall and comes to rest after the front of the car has collapsed 1 m. The man is wearing a seat bell and harness. What is the average force exerted by the belt and harness during the crash?
• When an object is thrown upward, it rises to a height ‘h’. How high is the object, in terms of h, when it has lost one-third of its original kinetic energy?
• A pump is needed to lift water through a height of 2.5 m at the rate of 500 g/min. What must the minimum horse power of the pump be?
• A horse pulls a cart horizontally with a force of 40 lb at an angle 30o above the horizontal and moves along at a speed of 6.0 miles/hr. (a) How much work does the horse do in 10 minutes? (b) What is the power out put of the horse?
• A body of mass ‘m’ accelerates uniformly from rest to a speed Vf in time tf. Show that the work done on the body as a function of time ‘t’, in terms of Vf and tf, is 
•  A rocket of mass 0.200 kg is launched from rest. It reaches a point p lying at a height 30.0 m above the surface of the earth from the starting point. In the process + 425 J of work is done on the rocket by the burning chemical propellant. Ignoring air-resistance and the amount of mass lost due to the burning propellant, find the speed Vf of the rocket at the point P.
• Two forces F1 = 3i-2j+ 5k and F2 = i +6 j +2k act on a body which is displaced along a vector r = 4i - j + 3k . Calculate the work done on the body
• A crane lifts a load of 6000 N through a vertical distance of 15 m in 30 s. What is the potential energy at the highest point of this operation?
• A horse pulls a cart horizontally with a force of 60 lb at an angle of 30 degrees above the horizontal and moves along at a speed of 8 miles per hour. How much work does the horse do in 15 minutes and whaTs the power output of the horse.(1 hp=550 lb-ft / sec) and (1 mile=5280 ft) 
• A 80 kg man runs up a hill through a height of 3m in 2 sec. What is his average power output?
• An object moves along a straight line in a force field from (3, 2, -6) to (14, 13, 9) when a uniform force F=4i + j + 3k acts on it. Find the work done.
• A horse pulls a cart horizontally with a force of 40 N at an angle of 25 degrees above the horizontal A U T H O R : M U H A M M A D T A L H A B I N Y O U S U F Page 158 and moves along at a speed of 15 m/s . How much work does the horse do in 5 minutes and what is the power output of the horse. Give your answer in horse power (1 hp=746 W) 
• An object weighing 98N is dropped from a height of 10m. It is found to be moving with a velocity 12m/sec just before it hits the ground. How large was the frictional force acting upon it?