Question

a boy of mass 45 kg climbs 20 steps of upstairs each of height 10 cm . calculate the potential energy the boy possess at the 20th step
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Answer 1

✯ Given :-

• Mass = 45kg
• Number of steps = 20
• Distance between each step = 10cm

✯ To find :-

• Potential energy ( P.E ) = ?

✯ Solution :-

Firstly ,

Total height = distance between each step × Total no. of steps

Substituting ,

• Total height = ?
• Distance between each step = 10cm
• Total nom of steps = 20

⇒ Total height = 10 × 20

⇒ Total height = 200 cm

As we know that

Potential energy (P.E) = m × g × h

Where ,

• m → mass = 45kg
• g → acceleration due to gravity = 10 m/s²
• h → height = 200cm = 0.2 m

⇒ P.E = 45 × 10 × 2/10

⇒ P.E = 45 × 2

⇒ Potential energy ( P.E ) = 90 J

Hence , potential energy ( P.E ) = 90J