Kinetic Energy

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A 2 kg mass increases speed from 3 m/s to 7 m/s. Change in kinetic energy is:

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40 J

28 J

20 J

56 J

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Subject: physics
Chapter: work, energy and power
Topic: kinetic energy
Difficulty: Easy
Year: 2025

Solution

Correct Answer:

40 J

Kinetic Energy ( $K$ ) is given by $\frac{1}{2} m v^{2}$ .

Initial KE ( $K_{i}$ ): $\frac{1}{2} (2) (3^{2}) = 9 J$
Final KE ( $K_{f}$ ): $\frac{1}{2} (2) (7^{2}) = 49 J$
Change in KE ( $Δ K$ ): $K_{f} - K_{i} = 49 - 9 = 40 Joules$ . Alternatively, $Δ K = \frac{1}{2} m (v^{2} - u^{2}) = \frac{1}{2} (2) (49 - 9) = 40 J$ .

This easy difficulty physics question is from the chapter work, energy and power, covering the topic of kinetic energy. It appeared in the 2025 exam.

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