Question

4. A box of mass 2 kg is pushed along a floor
through 2m against a force of friction 5N.
The same box is lifted up through a height
of 2m. What will be the work done in both
cases respectively (g = 9.8 m/s2)
1) 10 J, 39.2J
2) 15 J, 36.2)
9. i 8
3) 12 J, 39.2J
4) 10 J, 32.9 J
a. 4=r
9.82
9 st​

Answer 1

Answer:

• (1) 10 J , 39.2 J is the required option

Explanation:

Solution :-

• Mass ,m1 = 2 kg
• Displacemet ,s1 = 2 m
• acceleration due to gravity,g = 9.8
• Force ,F = 5 N

As we know that Work Done is defined as the product of force and displacemet.

• W = Fs

As F = ma

Substitute the value we get

→ W1 = 5×2

→ W1 = 10 J

• Hence, Work Done by body in 1st case is 10 J Joules.

Now , Calculating the work done in 2nd case.

• mass ,m2 = 2 kg
• height ,h = 2 m
• Acceleration due to gravity ,g = 9.8m/s²

• W2 = mgh

Substitute the value we get

→ W2 = 2×9.8×2

→ W2 = 19.6×2

→ W2 = 39.2 J

• Hence, the work done by the body in 2nd case is 39.2 Joules.

Required option is (1) 10 J , 39.2 J

Answer 2

Case 1:-

Given:-

• Mass = 2kg
• Acceleration due to gravity = 9.8m/s²

We know that:-

W = Fs

W1 = 5 × 2

W1 = 10J

Hence,

• Work done = 10J

Case 2:-

W2 = mgh

W2 = 2 × 9.8 × 2

W2 = 19.6 × 2

W2 = 39.2 J

Hence,

• Work done = 39.2 J