Question

A box of mass 1kg is pulled through 1m along a level floor by a horizontal force of 8N. The box is then raised vertically onto a bench 2m high. If g=10m/s², calculate the total work done.​

Answer 1

Mass of the box (m) = 1 kg

Displacement (s) = 1 m

Horizontal force (F) = 8 N

Work Done : It is defined as product of force and displacement .

→ W = F.s

⇒ W = (8)(1)

⇒ W = 8 J

Now , Box is raised vertically onto a bench of 2 m high

→ W = - ΔU

⇒ W = - ( U₂ - U₁ )

⇒ W = U₁ - U₂

⇒ W = mgH₁ - mgH₂

⇒ W = mg(H₁ - H₂)

⇒ W = (1)(-10)(0 - 2)

⇒ W = (-10)(-2)

⇒ W = 20 J

Total work done = 8 J + 20 J = 28 J

Answer 2

Given :

• Mass = 1kg
• Horizontal displacement = 1m
• Force applied = 8N
• Height = 2m
• g= 10m/s2

━━━━━━━━━━━━━━━━━━

Need to find:

• The total work done =?

━━━━━━━━━━━━━━━━━━

Solution:

The work done while moving the box horizontally:

= F × s

= 8N × 1m

=$\purple{\bold{\boxed{ 8J----i}}}$

━━━━━━━━━━━━━━━━━━

Work done while lifting the box:

= mgh

= 1 × 10 × 2 J

=$\purple{\bold{\boxed{ 20J---ii}}}$

━━━━━━━━━━━━━━━━━━

Now total Work done:

= Work done while moving the box horizontally+ Work done while lifting it up

(adding i and ii, we get:)

Total Work done =8J+ 20J

⟹ Total Work done = 28J

━━━━━━━━━━━━━━━━━━

$\red{\bold{\large{\boxed{\boxed{\therefore Work\:done= </p><p>28J}}}}}$