Question

1. A man lifts a brick of mass 5 kg from the floor to a shelf 2 metres high. How much work is done
2. A toy car of mass 2 kg is moving with a velocity 4 m/s. Calculate the kinetic
3. The Leaning Tower of Pisa is 45 m high. A mass of 4 kg is dropped from the
potential energy at the top.
energy
of the toy car
.
TOP.
Calculate its​

Answer 1

QUESTION-1 :-

Given :-

• Mass of the body is 5 kg
• Height of the body is 2m

To find :-

• Work done

Solution :-

As we know that here Work done by the body is Potential energy So,

W = mgh

• m = mass
• g = gravity (9.8)
• h = height

Substituting the values ,

w = (5)(9.8)(2)

w = 10(9.8)

w= 98J

So, work done by the body is 98J

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QUESTION - 2 :-

Given :-

• Mass of the car is 2kg
• velocity of the car is 4 m/s

To find :-

• Kinetic energy

Solution :-

We have formula to find the Kinetic energy that is

K.E = ½ mv²

• m = mass
• v= velocity

Substituting the values,

K.E = ½(2) (4)²

K.E = (4)²

K.E = 16 J

So, the Kinetic energy of the body is 16J

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QUESTION- 3 :-

Given :-

• Height of the body is 45 m
• Mass of the body is 4 kg

To find :-

• Potential energy

Solution :-

As we know the formula to find Potential energy that is

P.E = mgh

• m = mass
• g = gravity(9.8)
• h = height

Substituting the values,

P.E = (4)(9.8)(45)

P.E = 180 ×9.8

P.E = 1764 J

So , Potential energy of the body is 1764 J