Work, Power and EnergyHard
Question
A 1000 kg elevator rises from rest in the basement to the fourth floor, a distance of 20 m. As it passes the fourth floor its speed is 4m/sec. There is a constant frictional force of 500 N. The work done by the lifting mechanism is:-
Options
A.196 × 103 J
B.204 × 103 J
C.214 × 103 J
D.203 × 105 J
Solution
Work done against gravitational force = mgh
= 1000 × 9.8 × 20 = 196 × 103 J
Work done to impart velocity to the body
=
mV2
=103 × 16 = 8 × 103J
Work done against frictional force
= 500 × 20 = 10 × 103 J
Total work done = 214 × 103 J
= 1000 × 9.8 × 20 = 196 × 103 J
Work done to impart velocity to the body
=
mV2=
103 × 16 = 8 × 103JWork done against frictional force
= 500 × 20 = 10 × 103 J
Total work done = 214 × 103 J
Create a free account to view solution
View Solution FreeMore Work, Power and Energy Questions
A stone is projected vertically up to reach maximum height ′h′. The ratio of its kinetic energy to potential...Three different objects m1, m2 and m3 are allowed to fall from rest and from the same point O along three different fric...A network of four capacitors of capacity equal to C1 = C,C = 2C,C3 = 3C and C4 = 4C are conducted to a batter as shown i...Potential energy of a system comprising of point charges is U1.When a charge q is added in the system without disturbing...A vessel contains a mixture of one mole of oxygen and two moles of nitrogen at 300 K. The ratio of the average rotationa...