Question 165: Work, Energy and Power & Circular Motion

Question

Velocity-time graph for a body of mass 10 kg is shown in figure. Work-done on
the body in first two seconds of the motion is :

Accepted Answer

Here u = 50 m/s , what  t = 0
$$\alpha $$  =  $${{\Delta v} \over {\Delta t}}$$  =  $${{50 - 0} \over {0 - 10}}$$  =  $$-$$5 m/s
2
Speed of the body at t = 2 s
v   =   u + at
=  50 + ($$-$$ 5) $$ 	imes $$ 2
=  40 m/s
From work energy theorem,
$$\Delta $$w  =  $${1 \over 2}m{v^2} - {1 \over 2}m{u^2}$$
=  $${1 \over 2}$$ m(v
2
$$-$$u
2
)
= $${1 \over 2}$$ $$ 	imes $$ 10 $$ 	imes $$ (40
2
$$-$$ 50
2
)
=  5 $$ 	imes $$ ($$-$$10)(90)
=  $$-$$ 4500 J

Answer

12000 J

Answer

$$-$$ 12000 J

Answer

$$-$$ 4500 J

Answer

$$-$$ 9300 J

Work, Energy and Power & Circular Motion

Velocity-time graph for a body of mass 10 kg is shown in figure. Work-done on the body in first two seconds of the motion is :

Choose the correct answer: