Chapter 5 – Work, Energy and Power
Sahay Sir > Question Answers > NCERT Exemplar Class 11 > Physics > Chapter 5 - Work, Energy and Power
Two inclined frictionless tracks, 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?
09
Nov
Two inclined frictionless tracks, 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? one gradual and the other steep meet at A from where two stones are allowed to [...]
A person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m 1000 times. Assume that the potential energy lost each time she lowers the mass is dissipated. (a) How much work does she do against the gravitational force? (b) Fat supplies 3.8 ×10^7 J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?
30
Oct
A person trying to lose weight (dieter) lifts a 10 kg mass, one thousand times, to a height of 0.5 m 1000 times. Assume that the potential energy lost each time she lowers the mass is dissipated. (a) How much work does she do against the gravitational force? (b) Fat supplies 3.8 ×10^7 J of [...]
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A molecule in a gas container hits a horizontal wall with speed 200 m s^−1 and angle 30 degree with the normal ,
A person trying to lose weight (dieter) lifts a 10 kg mass ,
and rebounds with the same speed. Is momentum conserved in the collision ? Is the collision elastic or inelastic ? ,
one thousand times ,
The blades of a windmill sweep out a circle of area A. (a) If the wind flows at a velocity v perpendicular to the circle, then the mass of the air of density ρ passing through it in time t is ?
30
Oct
The blades of a windmill sweep out a circle of area A. (a) If the wind flows at a velocity v perpendicular to the circle, then the mass of the air of density ρ passing through it in time t is ? The blades of a windmill sweep out a circle of area A. (a) [...]
A particle of mass 0.5 kg travels in a straight line with velocity v=ax^3/2 where a=5m^−1/2s^−1. What is the work done by the net force during its displacement from x=0 to x=2m?
30
Oct
A particle of mass 0.5 kg travels in a straight line with velocity v=ax^3/2 where a=5m^−1/2s^−1. What is the work done by the net force during its displacement from x=0 to x=2m? A particle of mass 0.5 kg travels in a straight line with velocity v=ax^3/2 where a=5m^−1/2s^−1. What is the work done by the [...]
The bob A of a simple pendulum is released from a horizontal position A as shown in in figure. If the length of the pendulum is 1.5m , what is the speed with which the bob arrives at the lowermost point B, given that it dissipates 5% of its initial energy against air resistance ?
30
Oct
The bob A of a simple pendulum is released from a horizontal position A as shown in in figure. If the length of the pendulum is 1.5m , what is the speed with which the bob arrives at the lowermost point B, given that it dissipates 5% of its initial energy against air resistance ? [...]
Two identical ball bearing in contact with each other and resting on a frictionless table are hit head-on by another ball bearing of the same mass moving initially with a speed V. If the collision is elastic, which of the following (figure above) is a possible result after collision?
30
Oct
Two identical ball bearing in contact with each other and resting on a frictionless table are hit head-on by another ball bearing of the same mass moving initially with a speed V. If the collision is elastic, which of the following (figure above) is a possible result after collision? a motorist follows a track that [...]
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a motorist follows a track that turns to his left by an angle of 60° after every 500 m. Starting from a given turn ,
On an open ground ,
sixth and eighth turn. Compare the magnitude of the displacement with the total path length covered by the motorist in each case. ,
specify the displacement of the motorist at the third ,
A pump on the ground floor of a building can pump up water to fill a tank of volume 30 m 15 min. If the tank is 40 m above the ground, and the efficiency of the pump is 30%, how much electric power is consumed by the pump? (Take g = 10 ms^−2 ).
30
Oct
A pump on the ground floor of a building can pump up water to fill a tank of volume 30 m 15 min. If the tank is 40 m above the ground, and the efficiency of the pump is 30%, how much electric power is consumed by the pump? (Take g = 10 ms^−2 ). [...]
A molecule in a gas container hits a horizontal wall with speed 200 m s^−1 and angle 30 degree with the normal, and rebounds with the same speed. Is momentum conserved in the collision ? Is the collision elastic or inelastic ?
30
Oct
A molecule in a gas container hits a horizontal wall with speed 200 m s^−1 and angle 30 degree with the normal, and rebounds with the same speed. Is momentum conserved in the collision ? Is the collision elastic or inelastic ? A molecule in a gas container hits a horizontal wall with speed 200 [...]
A rain drop of radius 2 mm falls from a height of 500 m above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey? What is the work done by the resistive force in the entire journey, if its speed on reaching the ground is 10 ms^–1?
30
Oct
A rain drop of radius 2 mm falls from a height of 500 m above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height, it attains its maximum (terminal) speed, and moves with uniform speed thereafter. What is the work done by the gravitational [...]
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a motorist follows a track that turns to his left by an angle of 60° after every 500 m. Starting from a given turn ,
A rain drop of radius 2 mm falls from a height of 500 m above the ground. It falls with decreasing acceleration (due to viscous resistance of the air) until at half its original height ,
it attains its maximum (terminal) speed ,
On an open ground ,
sixth and eighth turn. Compare the magnitude of the displacement with the total path length covered by the motorist in each case. ,
specify the displacement of the motorist at the third ,
An electron and a proton are detected in a cosmic ray experiment, the first with kinetic energy 10 keV, and the second with 100 keV. Which is faster the electron or the proton? Obtain the ratio of their speeds. (electron mass = 9.1×10^−31 kg, proton mass = 1.67×10^−27 kg,1eV = 1.6×10^−19 J)
30
Oct
An electron and a proton are detected in a cosmic ray experiment, the first with kinetic energy 10 keV, and the second with 100 keV. Which is faster the electron or the proton? Obtain the ratio of their speeds. (electron mass = 9.1×10^−31 kg, proton mass = 1.67×10^−27 kg,1eV = 1.6×10^−19 J) 1eV = [...]
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1eV = 1.6×10^−19 J) ,
An electron and a proton are detected in a cosmic ray experiment ,
and the second with 100 keV. Which is faster the electron or the proton? Obtain the ratio of their speeds. (electron mass = 9.1×10^−31 kg ,
proton mass = 1.67×10^−27 kg ,
the first with kinetic energy 10 keV ,