iGCSE Physics (0625) 1.7.4 Power-Exam Style Questions- New Syllabus
▶️ Answer/Explanation
Detailed solution:
To find the useful energy transferred, we use the power formula: $P = \frac{\Delta E}{t}$.
First, convert the time from minutes to the SI unit of seconds: $t = 2.0 \times 60 = 120\text{ s}$.
Rearranging the formula to solve for energy gives: $\Delta E = P \times t$.
Substitute the given values: $\Delta E = 60\text{ W} \times 120\text{ s} = 7200\text{ J}$.
This calculation shows that the total useful energy transferred by the boy is $7200\text{ J}$.
Thus, option D is the correct answer.
Question
A man can either take an escalator or a lift to travel up between two floors in a hotel.
The escalator takes 20 seconds to carry the man between the two floors. The useful work done against gravity is W. The useful power developed is P.
The lift takes 30 seconds to carry the same man between the same two floors.
How much useful work against gravity is done by the lift, and how much useful power is developed by the lift?
| useful work done against gravity by lift | useful power developed by lift |
A | more than W | less than P |
B | more than W | P |
C | W | less than P |
D | W | P |
Answer/Explanation
Ans: C
Question
The engine of a motor vehicle develops a large amount of power.
Which statement is correct?
The driving force acting on the vehicle must be large.
The engine must have a very large volume.
The engine must transfer large amounts of energy each second.
The vehicle must be very fast.
Answer/Explanation
Ans: C