Question

1)A person exerts 20 N of force and displaces a trolley by 15 m in the direction of force .Work done by him will be

(a) 3000 J (b) 3) (c) 300 J (d) 30 J

2) Work done by the person in the above case is

(a) Negative (b) positive (c) zero (d) none of the above

3) Work done by gravity on horizontally moving trolley is O because the angle between the force of gravity and displacement is

(a) 0° (b) 60° (c) 90° (d) 45°

4) The formula for work done is

(i) F/s (ii) s/F (iii) 1/F (iv) F.s cos0​

Answer 1

Answer:

1. A person exerts 20 N of force and displaces a trolley by 15 m in the direction of force .Work done by him will be

option c) 300J

work done = force × displacement

= 20N × 15m

= 300J

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2. Work done by the person in the above case is

option b ) positive

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3. Work done by gravity on horizontally moving trolley is O because the angle between the force of gravity and displacement is

option a) 0°

Let's start with a reasonable assumption that bag is carried toward the truck with the constant velocity. In case of constant velocity, according to 1st Newton law, the net forces equals zero. There are only two forces acting on the bag: the force of gravity (vertically down), and the force of Sally (vertically up). Therefore there is no horizontal force in direction of the truck.

━━━━━━━━━━━━━━━━━━

4. The formula for work done is

option d ) F.s cosθ

Answer 2

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Question:1

1)A person exerts 20 N of force and displaces a trolley by 15 m in the direction of force .Work done by him will be:

(a) 3000 J (b) 3) (c) 300 J (d) 30 J

Answer:

(c) 300j

F = 20N

S = 15m

Work done,

W = F × S

$\rightarrow$ 20 × 15

$\rightarrow$ 300 J

Question:2

Work done by the person in the above case is

(a) Negative (b) positive (c) zero (d) none of the above

Answer:

(c)Zero

Question:3

Work done by gravity on horizontally moving trolley is O because the angle between the force of gravity and displacement is

(a) 0° (b) 60° (c) 90° (d) 45°

Answer:

(a)0°

Question:4

The formula for work done is

(i) F/s (ii) s/F (iii) 1/F (iv) F.s cos0​

Answer:

(iv)F.s cos theta