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Q.7. Solve the following problems.

(a) Radha takes 15 s to carry a bag weighing 18 kg to a height of 5 m. How much power has she used?

Ans.


Sagot :

To solve this problem, we need to determine the power used by Radha to carry the bag. Power is defined as the rate at which work is done. Here's the step-by-step solution:

1. Determine the Force Exerted:
- The weight of the bag is 18 kg.
- The force exerted due to gravity is calculated as:
[tex]\[ \text{Force} = \text{mass} \times \text{acceleration due to gravity} \][/tex]
Given:
[tex]\[ \text{mass} = 18 \, \text{kg} \][/tex]
[tex]\[ \text{acceleration due to gravity} = 9.8 \, \text{m/s}^2 \][/tex]

Therefore:
[tex]\[ \text{Force} = 18 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 176.4 \, \text{N} \][/tex]

2. Calculate the Work Done:
- Work is the product of the force exerted and the distance moved in the direction of the force.
[tex]\[ \text{Work} = \text{Force} \times \text{Distance} \][/tex]
Given:
[tex]\[ \text{Distance} = 5 \, \text{m} \][/tex]

Therefore:
[tex]\[ \text{Work} = 176.4 \, \text{N} \times 5 \, \text{m} = 882.0 \, \text{J} \][/tex]

3. Calculate the Power Used:
- Power is defined as the rate of doing work, which can be calculated using the formula:
[tex]\[ \text{Power} = \frac{\text{Work}}{\text{Time}} \][/tex]
Given:
[tex]\[ \text{Time} = 15 \, \text{s} \][/tex]

Therefore:
[tex]\[ \text{Power} = \frac{882.0 \, \text{J}}{15 \, \text{s}} = 58.8 \, \text{W} \][/tex]

Thus, Radha has used a power of 58.8 watts to carry the bag.

The final results are:
- Force Exerted: 176.4 N
- Work Done: 882.0 J
- Power Used: 58.8 W