# Work, Energy, and Power - Class 11 - Physics

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## Extra Questions - Work, Energy, and Power | NCERT | Physics | Class 11

A person carrying a bag of total mass $25 \mathrm{~kg}$ climbs up to a height of $5 \mathrm{~m}$ in 30 seconds slowly. The power delivered for carrying the bag is:

A) $40.83 \mathrm{~W}$

B) $19.67 \mathrm{~W}$

C) $26.23 \mathrm{~W}$

D) $38.15 \mathrm{~W}$

The correct answer is **Option A: $40.83 \mathrm{~W}$**.

To solve this problem, we'll start by calculating the **force exerted by the person**, which is equal to the weight of the bag. This force ($F$) is given by:
$$
F = mg = 25 , \text{kg} \times 9.8 , \text{m/s}^2 = 245 , \text{N}
$$

Next, we calculate the **work done** ($W$) by this force to lift the bag to a height of $5 , \text{m}$:
$$
W = F \times h = 245 , \text{N} \times 5 , \text{m} = 1225 , \text{J}
$$

Since the **work is done over a period** of 30 seconds, we can find the **power delivered** ($P$) using the formula:
$$
P = \frac{W}{t} = \frac{1225 , \text{J}}{30 , \text{s}} = 40.83 , \text{W}
$$

Thus, the power delivered for carrying the bag is **$40.83 \mathrm{~W}$**.

The commercial unit of energy consumption in households, industries, and commercial establishments is:

A. $\mathrm{kW}$

B. $\mathrm{kWh}$

C. Joule

D. Watt

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Is it possible to find the electrical energy in terms of $\mathrm{kJ}$ if the power consumed by a toaster in 15 min is 125 $\mathrm{W}$?

A) 112.5 $\mathrm{kJ}$

B) 112.05 $\mathrm{kJ}$

C) 11.25 $\mathrm{kJ}$

D) 1125 $\mathrm{kJ}$