A spring of constant 500 N/m is stretched by 0.2 m. How much energy is stored in it?
Answer and explanation
Correct answer: C. 10 J
- Step 1: Elastic energy = ½kx². Step 2. E = ½ × 500 × 0.2² = 10 J. Answer: 10 J. Why not the others: 20 J is what you get if you forget the factor ½. 50 J is what you get if you forget to square the extension. 100 J is what you get if you give the force instead.
Practise more Mechanics, heat and electricity.
Free questions with an explanation for every one, and full timed JEE Advanced mock tests.
More Mechanics, heat and electricity questions
- What force gives a mass of 7 kg an acceleration of 7 m/s²?
- How much gravitational potential energy does a 10 kg mass gain when lifted 2 m? (take g = 10 m/s²)
- A machine does 1200 J of work in 60 s. What is its power?
- A force of 600 N acts on an area of 0.2 m². What pressure does it exert?
- A wave has a frequency of 500 Hz and a wavelength of 4 m. What is its speed?
- A wire 2 m long carries 5 A at right angles to a magnetic field of 0.5 T. What force acts on it?