A body of mass 2 kg is dropped from a height of 10 meters. Due to air resistance, it hits the ground with a speed of 12 m/s. What is the work done by air resistance?

B. -56 J — Apply the work-energy theorem: the change in kinetic energy equals the sum of work done by gravity and work done by air resistance. Calculate initial and final kinetic energies and the work done by gravity.

JEE Main · PhysicsMedium

$A body of mass $m = 2 \text{ kg}$ is dropped from a height $h = 10 \text{ m}$. Due to air resistance, it hits the ground with a speed $v = 12 \text{ m/s}$. What is the work done by air resistance? (Take $g = 10 \text{ m/s}^2$)$

A. $-40 \text{ J}$
B. $-56 \text{ J}$
C. $-20 \text{ J}$
D. $-100 \text{ J}$

Show correct answer & step-by-step solution

Correct answer: B — $-56 \text{ J}$

Solution

Δ K = W_{g} + W_{ai r}

\frac{1}{2} m v^{2} - 0 = m g h + W_{ai r}

0.5 \times 2 \times 144 = 2 \times 10 \times 10 + W_{ai r}

144 = 200 + W_{ai r}

, so

W_{ai r} = - 56 J

Attempt this question & track your score

Attempt & Track Free →

More Work Energy Power practice questions

A force of 10 Newtons acts on a body and displaces it by 5 meters in the direction of the force. Calculate the work done
A body of mass 2 kg is moving with a velocity of 4 meters per second. What is its kinetic energy in Joules?
An object of mass 5 kg is raised to a height of 10 meters above the ground. Calculate the potential energy gained by the
A machine does 400 Joules of work in 20 seconds. What is the power of the machine in Watts?
If the velocity of a body is doubled, its kinetic energy becomes how many times its original value?
$A p a r t i c l eo f ma ss 2 k g m o v es u n d er t h e in f l u e n ceo f a f or ce F = (3 t^{2} i + 4 t j) N . I f t h e p a r t i c l es t a r t s f r o m r es t a t$
A block of mass 1 kg is pushed against a spring with spring constant 100 N/m, compressing it by 0.2 m. When released, th
A force F = (2x + 3) N acts on a particle moving along the x-axis. What is the work done by this force as the particle m
An engine pumps water continuously through a hose. Water leaves the hose with a velocity v and m is the mass per unit le
$A p a r t i c l eo f ma ss mm o v es ina p o t e n t ia l f i e l d U (x) = a / x^{2} - b / x, w h er e aan d ba r e p os i t i v eco n s t an t s . W ha t i s t h e p e$
A block of mass m is attached to a spring of constant k and is placed on a rough horizontal surface with coefficient of
A chain of mass M and length L is held on a frictionless table with 1/n of its length hanging over the edge. If the chai

View all Work Energy Power questions →