Tutorial – Work, Energy
Tutorial – Work, Energy
(Assume the acceleration due to gravity, g = 9.81 m/s2 )
1. Calculate the work done when a force of 40 N pushes an object a distance of
500 m in the same direction as the force.
2. Calculate the work done when a mass is lifted vertically by a crane to a height of 5 m, the force required to lift the mass being 98 N.
3. A spring, initially in a relaxed state, is extended by 100 mm. Determine the work done by using a work diagram if the spring requires a force of 0.6 N per mm of stretch.
4. A spring requires a force of 10 N to cause an extension of 50 mm. Determine the work done in extending the spring (a) from zero to 30 mm, and (b) from 30 mm to 50 mm.
5. Calculate the work done when a mass of 20 kg is lifted vertically through a distance of 5.0 m. Assume that the acceleration due to gravity is 9.81 m/s2 .
6. Water is pumped vertically upwards through a distance of 50.0 m and the work done is 294.3 kJ. Determine the number of litres of water pumped. (1 litre of water has a mass of 1kg).
7. Determine the work done when a force of 50 N pushes an object 1.5 km in the same direction as the force.
8. Calculate the work done when a mass of weight 200 N is lifted vertically by a crane to a height of 100m.
9. A spring requires a force of 50 N to cause an extension of 100 mm. Determine the work done in extending the spring (a) from 0 to 100 mm, and (b) from 40 mm to 100 mm.
10. A machine exerts a force of 200 N in lifting a mass through a height of 6 m. If 2 kJ of energy are supplied to it, what is the effiency of the machine?
11. Calculate the useful output energy of an electric motor which is 70 % efficient if it uses 600 J of electrical energy.
12. 4 kJ of energy are supplied to a machine used for lifting a mass. The force required is 800 N. If the machine has an effiency of 50 %, to what height will it lift the mass?
13. A hoist exerts a force of 500 n in raising a load through a height of 20
(Assume the acceleration due to gravity, g = 9.81 m/s2 )
1. Calculate the work done when a force of 40 N pushes an object a distance of
500 m in the same direction as the force.
2. Calculate the work done when a mass is lifted vertically by a crane to a height of 5 m, the force required to lift the mass being 98 N.
3. A spring, initially in a relaxed state, is extended by 100 mm. Determine the work done by using a work diagram if the spring requires a force of 0.6 N per mm of stretch.
4. A spring requires a force of 10 N to cause an extension of 50 mm. Determine the work done in extending the spring (a) from zero to 30 mm, and (b) from 30 mm to 50 mm.
5. Calculate the work done when a mass of 20 kg is lifted vertically through a distance of 5.0 m. Assume that the acceleration due to gravity is 9.81 m/s2 .
6. Water is pumped vertically upwards through a distance of 50.0 m and the work done is 294.3 kJ. Determine the number of litres of water pumped. (1 litre of water has a mass of 1kg).
7. Determine the work done when a force of 50 N pushes an object 1.5 km in the same direction as the force.
8. Calculate the work done when a mass of weight 200 N is lifted vertically by a crane to a height of 100m.
9. A spring requires a force of 50 N to cause an extension of 100 mm. Determine the work done in extending the spring (a) from 0 to 100 mm, and (b) from 40 mm to 100 mm.
10. A machine exerts a force of 200 N in lifting a mass through a height of 6 m. If 2 kJ of energy are supplied to it, what is the effiency of the machine?
11. Calculate the useful output energy of an electric motor which is 70 % efficient if it uses 600 J of electrical energy.
12. 4 kJ of energy are supplied to a machine used for lifting a mass. The force required is 800 N. If the machine has an effiency of 50 %, to what height will it lift the mass?
13. A hoist exerts a force of 500 n in raising a load through a height of 20