(A) The boy has to overcome the force of gravity to climb the stairs.Force of gravity on the boy,$F = m \times g = 40 \, kg \times 9.8 \, m s^{-2} = 3

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Work = $1960 \, J$,Power = $392 \, W$

(A) The boy has to overcome the force of gravity to climb the stairs.Force of gravity on the boy,$F = m \times g = 40 \, kg \times 9.8 \, m s^{-2} = 392 \, N$.Total height (distance) covered,$S = 50 \times 10 \, cm = 500 \, cm = 5 \, m$.$(i)$ Work done by the boy in climbing,$W = F \times S = 392 \, N \times 5 \, m = 1960 \, J$.$(ii)$ Power developed,$P = \frac{W}{t} = \frac{1960 \, J}{5 \, s} = 392 \, W$.

Class 9 Science WORK AND ENERGY Mix Example - WORK AND ENERGY

Medium

$A$ boy of mass $40 \, kg$ runs up a flight of $50$ steps,each $10 \, cm$ high,in $5 \, s$. Find: $(i)$ the work done by the boy,and $(ii)$ the power developed. $(g = 9.8 \, m s^{-2})$

A
Work = $1960 \, J$,Power = $392 \, W$
B
Work = $1960 \, J$,Power = $3920 \, W$
C
Work = $196 \, J$,Power = $39.2 \, W$
D
Work = $19600 \, J$,Power = $3920 \, W$

Explore More

Browse All

Question Bank

All Subjects

Class 9 Questions

Class 9

Science Questions

Chapter

WORK AND ENERGY

Subtopic

Mix Example - WORK AND ENERGY

$A$ weightlifter lifts $240 \,kg$ from the ground to a height of $2.5 \,m$ in $3 \,s$. The average power is:

Easy

View Solution

$A$ girl is carrying a school bag of $3 \, kg$ mass on her back and moves $200 \, m$ on a levelled road. The work done against the gravitational force will be $(g = 10 \, m \, s^{-2})$.

Medium

View Solution

$(i)$ Define power. Mention its $SI$ unit.
$(ii)$ $A$ boy of mass $50 \, kg$ runs up a staircase of $40$ steps in $8 \, s$. If the height of each step is $15 \, cm$,find his power. (Given,$g = 10 \, m \, s^{-2}$)

Medium

View Solution

State whether the following statement is true or false:
Work done by a force depends upon how fast work is done.

Easy

View Solution

$A$ body is moving with constant speed over a frictionless surface. What is the work done by the weight of the body?

Easy

View Solution

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial

For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free

For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo

$A$ boy of mass $40 \, kg$ runs up a flight of $50$ steps,each $10 \, cm$ high,in $5 \, s$. Find: $(i)$ the work done by the boy,and $(ii)$ the power developed. $(g = 9.8 \, m s^{-2})$

Similar Questions

$A$ weightlifter lifts $240 \,kg$ from the ground to a height of $2.5 \,m$ in $3 \,s$. The average power is:

$A$ girl is carrying a school bag of $3 \, kg$ mass on her back and moves $200 \, m$ on a levelled road. The work done against the gravitational force will be $(g = 10 \, m \, s^{-2})$.

$(i)$ Define power. Mention its $SI$ unit.$(ii)$ $A$ boy of mass $50 \, kg$ runs up a staircase of $40$ steps in $8 \, s$. If the height of each step is $15 \, cm$,find his power. (Given,$g = 10 \, m \, s^{-2}$)

State whether the following statement is true or false:Work done by a force depends upon how fast work is done.

$A$ body is moving with constant speed over a frictionless surface. What is the work done by the weight of the body?

Vedclass Test Series

Exam Paper Generator

Online Exam Module

$(i)$ Define power. Mention its $SI$ unit.
$(ii)$ $A$ boy of mass $50 \, kg$ runs up a staircase of $40$ steps in $8 \, s$. If the height of each step is $15 \, cm$,find his power. (Given,$g = 10 \, m \, s^{-2}$)

State whether the following statement is true or false:
Work done by a force depends upon how fast work is done.