Power
Physics ⇒ Mechanics
Power starts at 8 and continues till grade 12.
QuestionsToday has an evolving set of questions to continuously challenge students so that their knowledge grows in Power.
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See sample questions for grade 11
A 60 W light bulb is left on for 10 hours. How much energy does it consume in joules?
A car engine provides a constant power output. If the car's speed doubles, what happens to the force provided by the engine?
A crane lifts a 500 kg load at a constant speed to a height of 10 m in 20 seconds. What is the power output of the crane? (g = 9.8 m/s²)
A cyclist does 9000 J of work in 10 minutes. What is the average power output?
A motor does 1500 J of work in 5 seconds. What is its power output?
A person lifts a 20 kg box to a height of 2 m in 4 seconds. Calculate the power used. (Take g = 9.8 m/s²)
A student climbs a staircase of height 3 m in 6 seconds. If the student's mass is 50 kg, calculate the average power developed. (g = 9.8 m/s²)
Describe a real-life example where high power is required but not necessarily a large amount of work.
Explain the difference between average power and instantaneous power.
If a force of 10 N moves an object 5 m in 2 seconds in the direction of the force, what is the power delivered?
If a machine has a power rating of 2 kW, how much work can it do in 5 minutes?
If the velocity of an object is zero, what is the instantaneous power delivered by a force acting on it?
The power output of a machine is 500 W. If it operates for 3 minutes, how much work does it do?
A 1200 kg car accelerates uniformly from rest to 20 m/s in 10 seconds. Calculate the average power delivered by the engine during this time.
A 70 kg athlete runs up a flight of stairs 5 m high in 4 seconds. Calculate the average power output in watts. (g = 9.8 m/s2)
A conveyor belt moves 200 kg of material per minute to a height of 8 m. If the system operates at 75% efficiency and g = 9.8 m/s2, what is the actual power consumed by the motor?
A force F acts on an object moving with velocity v. The angle between the force and velocity is θ. Write the expression for the instantaneous power delivered by the force.
A machine is rated at 5 kW but operates at only 80% efficiency. How much useful work does it perform in 10 minutes?
A pump is used to lift water from a well 15 m deep at a rate of 0.05 m3/min. If the density of water is 1000 kg/m3 and g = 9.8 m/s2, calculate the minimum power required by the pump in watts.
Explain why the power required to maintain a constant speed up a hill is greater than the power required to maintain the same speed on a level road.
