Chapter 5 – Work, Energy and Power
Sahay Sir > Question Answers > NCERT Exemplar Class 11 > Physics > Chapter 5 - Work, Energy and Power
A family uses 8kW of power. (a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square metre. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8kW? (b) Compare this area to that of the roof of a typical house.
27
Nov
A family uses 8kW of power. (a) Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square metre. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8kW? (b) Compare this area to that of the [...]
On complete combustion, a liter of petrol gives off heat equivalent to 3×10^7 J. In a test drive a car weighing 1200 kg including the mass of driver, runs 15 km per liter while moving with uniform speed on a straight track. Assuming that friction offered by the road surface and air to be uniform. calculate the force of friction acting on the car during the drive, if the efficiency of the car engine were =0.5.
09
Nov
On complete combustion, a liter of petrol gives off heat equivalent to 3×10^7 J. In a test drive a car weighing 1200 kg including the mass of driver, runs 15 km per liter while moving with uniform speed on a straight track. Assuming that friction offered by the road surface and air to be uniform. [...]
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a liter of petrol gives off heat equivalent to 3×10^7 J. In a test drive a car weighing 1200 kg including the mass of driver ,
On complete combustion ,
one gradual and the other steep meet at A from where two stones are allowed to slide down from rest ,
one on each tracks as shown in figure. Which of the following statements is correct? ,
Two inclined frictionless tracks ,
An adult weighing 600N raises the centre of gravity of his body by 0.25m while taking each step of 1m length in jogging. If he jogs for 6km, calculate the energy utilised by him in jogging assuming that there is no energy loss dur to friction of ground and air. Assuming that the body of the adult is capable of converting 10% of energy intake in the form of food, calculate the energy equivalent of food that would be required to compensate energy utilised for jogging.
09
Nov
An adult weighing 600N raises the centre of gravity of his body by 0.25m while taking each step of 1m length in jogging. If he jogs for 6km, calculate the energy utilised by him in jogging assuming that there is no energy loss dur to friction of ground and air. Assuming that the body of [...]
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An adult weighing 600N raises the centre of gravity of his body by 0.25m while taking each step of 1m length in jogging. If he jogs for 6km ,
one gradual and the other steep meet at A from where two stones are allowed to slide down from rest ,
one on each tracks as shown in figure. Which of the following statements is correct? ,
Two inclined frictionless tracks ,
An engine is attached to a wagon through a shock absorber of length 1.5 m. The system with a total mass of 50,000 kg is moving with a speed of 36 km/h when the brakes are applied to bring it to rest. In the process of the system being brought to rest, the spring of the shock absorber gets compressed by 1.0 m. If 90% of energy of the wagon is lost due to friction, calculate the spring constant.
09
Nov
An engine is attached to a wagon through a shock absorber of length 1.5 m. The system with a total mass of 50,000 kg is moving with a speed of 36 km/h when the brakes are applied to bring it to rest. In the process of the system being brought to rest, the spring of [...]
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000 kg is moving with a speed of 36 km/h when the brakes are applied to bring it to rest. In the process of the system being brought to rest ,
An engine is attached to a wagon through a shock absorber of length 1.5 m. The system with a total mass of 50 ,
calculate the spring constant. ,
the spring of the shock absorber gets compressed by 1.0 m. If 90% of energy of the wagon is lost due to friction ,
Suppose the average mass of raindrops is 3.0×10^−5 kg and their average terminal velocity 9ms^−1. Calculate the energy transferred by rain to each square metre of the surface at the place which receives 100 cm of rain in a year.
09
Nov
Suppose the average mass of raindrops is 3.0×10^−5 kg and their average terminal velocity 9ms^−1. Calculate the energy transferred by rain to each square metre of the surface at the place which receives 100 cm of rain in a year. one gradual and the other steep meet at A from where two stones are allowed [...]
Two pendulums with identical bobs and length are suspended from a common support such that in rest position the two bobs are in contact. One of the bobs is released after being displaced by 10^o so that it collides elastically head on with the other bob. (a) Describe the motion of two bobs. (b) Draw a graph showing variation in energy of either pendulum with time, for 0 ≤ t ≤ 2T, where T is the period of each pendulum.
09
Nov
Two pendulums with identical bobs and length are suspended from a common support such that in rest position the two bobs are in contact. One of the bobs is released after being displaced by 10^o so that it collides elastically head on with the other bob. (a) Describe the motion of two bobs. (b) Draw [...]
A raindrop of mass 1.00 g falling from a height of 1 km hits the ground with a speed of 50 m s^–1. Calculate (a) the loss of P.E. of the drop. (b) the gain in K.E. of the drop. (c) Is the gain in K.E. equal to loss of P.E.? If not why. Take g = 10 m s^2
09
Nov
A raindrop of mass 1.00 g falling from a height of 1 km hits the ground with a speed of 50 m s^–1. Calculate (a) the loss of P.E. of the drop. (b) the gain in K.E. of the drop. (c) Is the gain in K.E. equal to loss of P.E.? If not why. Take [...]
The bob A of a pendulum released from horizontal to the vertical hits another bob B of the same mass at rest on a table as shown in figure. If the length of the pendulum is 1m, calculate (a) the height to which bob A will rise after collision. (b) the speed with which bob B starts moving. Neglect the size of the bobs and assume the collision to be elastic.
09
Nov
The bob A of a pendulum released from horizontal to the vertical hits another bob B of the same mass at rest on a table as shown in figure. If the length of the pendulum is 1m, calculate (a) the height to which bob A will rise after collision. (b) the speed with which bob [...]
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calculate (a) the height to which bob A will rise after collision. (b) the speed with which bob B starts moving. Neglect the size of the bobs and assume the collision to be elastic. ,
The bob A of a pendulum released from horizontal to the vertical hits another bob B of the same mass at rest on a table as shown in figure. If the length of the pendulum is 1m ,
Consider a one-dimensional motion of a particle with total energy E. There are four regions A, B, C and D is which the relation between potential energy U, kinetic energy (K) and total energy E is as given below Region A:V>E Region B:V
09
Nov
Consider a one-dimensional motion of a particle with total energy E. There are four regions A, B, C and D is which the relation between potential energy U, kinetic energy (K) and total energy E is as given below Region A:V>E Region B:V B C and D is which the relation between potential energy U [...]
A ball of mass m, moving with a speed 2v0, collides inelastically (e > 0) with an identical ball at rest. Show that (a) For head-on collision, both the balls move forward. (b) For a general collision, the angle between the two velocities of scattered balls is less than 90°.
09
Nov
A ball of mass m, moving with a speed 2v0, collides inelastically (e > 0) with an identical ball at rest. Show that (a) For head-on collision, both the balls move forward. (b) For a general collision, the angle between the two velocities of scattered balls is less than 90°. A ball of mass m [...]