PHYSICS: WORK, ENERGY, POWER, EFFICIENCY PRACTICE WORD PROBLEMS
PHYSICS
WORK, ENERGY, POWER, EFFICIENCY
PRACTICE WORD PROBLEMS WITH SOLUTIONS
Practice Word Problems:
WORK
Find the work done in:
a) Applying a force of 60N at an angle of 30 º with the horizontal in moving a box for a distance of 20m.
b) Transferring a sack of rice (50kg) from the floor to the shelf 2.5m above the floor.
c) Raising a box with a weight of 75N upward to a distance of 12m high.
d) A 68kg man climbs 800m high mountain in 2.5h. calculate the work done.
ENERGY
Potential Energy
1) Calculate the work done in carrying chalk (20kg) on top of the table which is 0.6m from the floor.
2) A chair with a mass of 3kg is lifted using a rope 12m high. How much work is done?
3) Calculate the potential energy of the water in a lake of a volume of 100k𝑚2 (mass = 1 x 1014 𝑘𝑔). If the average
height of the lake is 50m from the base.
Kinetic Energy
1) How much energy is required to accelerate a vehicle with a mass of 50kg from 10m/s to 90m/s assuming there is
no friction?
2) A baseball player exerts a force of 220N to throw the ball out a large distance. Calculate the speed of the ball if its
mass is 400g and it landed at a distance of 50m.
3) A baseball player exerts a force of 200N upon throwing a ball with a velocity of 40m/s to a distance of 15m. find
the mass of the ball.
POWER
1) Calculate the power (w and hp) of a person (55kg):
a) In climbing a stair 20m high in 65 seconds
b) And in running the same stair in 20 seconds
c) A 68kg man climbs 800m high mountain in 2.5h. calculate his power.
EFFICIENCY
1) A powerplant has an efficiency of 38 % and generates 1,500mw of electricity. What is the plant’s rate of production
of waste energy?
2) The efficiency of the human body is converting food energy into work which varies with activity. In climbing stairs,
the efficiency is 20 %. How much food energy in Kcal does a person with a mass of 50kg needs in climbing 30m
high stairs in 25 seconds?
3) What is the cost of turning on a 400w TV at 6hors per day for 30days if the cost of the electric energy is Php
3.00/kWh?
4) What is the efficiency of the bulb that consumes 60w of electric power and puts out 10w of visible light?
5) A 68kg man climbs 800m high mountain in 2.5h. What is his efficiency during the climb?
WORK, ENERGY, AND POWER IN THE HUMAN BODY
1) How many grams of fat will you gain if you are ideal, and you consume 2800Kcal?
2) A cyclist traveling 21/hr consumes oxygen at 2L/min. a man sleeping will consume .24L/min oxygen. What is the
ratio of the respiratory rate of these 2 men consume in one hour?
3) A 68kg man climbs 800m high mountain in 2.5h. What is his power consumption if he uses 9.6Kcal/min
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PHYSICS
WORK, ENERGY, POWER, EFFICIENCY
PRACTICE WORD PROBLEMS WITH SOLUTIONS
Practice Word Problems:
WORK
Find the work done in:
a) Applying a force of 60N at an angle of 30 º with the horizontal in moving a box for a distance of 20m.
b) Transferring a sack of rice (50kg) from the floor to the shelf 2.5m above the floor.
c) Raising a box with a weight of 75N upward to a distance of 12m high.
d) A 68kg man climbs 800m high mountain in 2.5h. calculate the work done.
ENERGY
Potential Energy
1) Calculate the work done in carrying chalk (20kg) on top of the table which is 0.6m from the floor.
2) A chair with a mass of 3kg is lifted using a rope 12m high. How much work is done?
3) Calculate the potential energy of the water in a lake of a volume of 100k𝑚2 (mass = 1 x 1014 𝑘𝑔). If the average
height of the lake is 50m from the base.
Kinetic Energy
1) How much energy is required to accelerate a vehicle with a mass of 50kg from 10m/s to 90m/s assuming there is
no friction?
2) A baseball player exerts a force of 220N to throw the ball out a large distance. Calculate the speed of the ball if its
mass is 400g and it landed at a distance of 50m.
3) A baseball player exerts a force of 200N upon throwing a ball with a velocity of 40m/s to a distance of 15m. find
the mass of the ball.
POWER
1) Calculate the power (w and hp) of a person (55kg):
a) In climbing a stair 20m high in 65 seconds
b) And in running the same stair in 20 seconds
c) A 68kg man climbs 800m high mountain in 2.5h. calculate his power.
EFFICIENCY
1) A powerplant has an efficiency of 38 % and generates 1,500mw of electricity. What is the plant’s rate of production
of waste energy?
2) The efficiency of the human body is converting food energy into work which varies with activity. In climbing stairs,
the efficiency is 20 %. How much food energy in Kcal does a person with a mass of 50kg needs in climbing 30m
high stairs in 25 seconds?
3) What is the cost of turning on a 400w TV at 6hors per day for 30days if the cost of the electric energy is Php
3.00/kWh?
4) What is the efficiency of the bulb that consumes 60w of electric power and puts out 10w of visible light?
5) A 68kg man climbs 800m high mountain in 2.5h. What is his efficiency during the climb?
WORK, ENERGY, AND POWER IN THE HUMAN BODY
1) How many grams of fat will you gain if you are ideal, and you consume 2800Kcal?
2) A cyclist traveling 21/hr consumes oxygen at 2L/min. a man sleeping will consume .24L/min oxygen. What is the
ratio of the respiratory rate of these 2 men consume in one hour?
3) A 68kg man climbs 800m high mountain in 2.5h. What is his power consumption if he uses 9.6Kcal/min
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