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Work and energy
Class 11 · Physics · 5 questions
Name: ____________________ Date: ____________
Work done by a force perpendicular to the displacement is:
- A Negative
- B Infinite
- C Zero
- D Maximum
A force of 10 N at 60 degrees to the displacement moves a body 4 m. The work done is:
- A 34.6 J
- B 40 J
- C 20 J
- D 10 J
The work energy theorem states that the net work done equals the change in:
- A Power
- B Momentum
- C Kinetic energy
- D Potential energy
A 1000 W motor lifts a load in 10 s. How much work does it do?
- A 100 J
- B 10000 J
- C 10 J
- D 1000 J
The escape speed from Earth is about:
- A 11.2 km/s
- B 1.1 km/s
- C 112 km/s
- D 3 x 10^5 km/s
Answer key
1. C, 2. C, 3. C, 4. B, 5. A
W = F d cos 90 = 0.
W = 10 x 4 x cos 60 = 20 J.
Net work = change in kinetic energy.
W = P t = 1000 x 10 = 10000 J.
Escape speed from Earth is about 11.2 km/s.