COMEDK · Physics · 6. Work Power Energy

An electric motor raises a mass of \(1.5 \mathrm{~kg}\), a distance of \(1.128 \mathrm{~m}\) in time of \(4.79 \mathrm{~s}\). Calculate the power to an appropriate significant figures.
(take \(g=9.81 \mathrm{~ms}^{-2}\))

A 3.46 W
B 3.5 W
C 3.465 W
D 3.47 W

Verified Solution

Answer & Solution

Correct Answer

(B) 3.5 W

Step-by-step Solution

Detailed explanation

The power \(P\) is defined as the rate of doing work, which is given by \(P = \dfrac{W}{t} = \dfrac{mgh}{t}\). Given values are \(m = 1.5 \text{ kg}\), \(g = 9.81 \text{ ms}^{-2}\), \(h = 1.128 \text{ m}\), and \(t = 4.79 \text{ s}\). Substituting these values into the formula:…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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An electric motor raises a mass of \(1.5 \mathrm{~kg}\), a distance of \(1.128 \mathrm{~m}\) in time of \(4.79 \mathrm{~s}\). Calculate the power to an appropriate significant figures.(take \(g=9.81 \mathrm{~ms}^{-2}\))

Step-by-step Solution

An electric motor raises a mass of \(1.5 \mathrm{~kg}\), a distance of \(1.128 \mathrm{~m}\) in time of \(4.79 \mathrm{~s}\). Calculate the power to an appropriate significant figures.
(take \(g=9.81 \mathrm{~ms}^{-2}\))