Work and Energy — Physics STD 11 Science — Question

Three particles of mass m each are placed at the three corners of an equilateral triangle of side a. Find the work which should be done on this system to increase the sides of the triangle to 2a.

Calculate the power developed by a person, while eating 100g of ice per minute. Latent heat of ice = 80cal/ g^-7.

The luminous flux of a monochromatic source of 1W is 450 lumen/ watt. Find the relative luminosity at the wavelength emitted.

(i) A motor cycle and a car is moving with the same velocity. Which of these have more momentum?
(ii) A motorcycle and car moving with same momentum. Which of these will have greater speed?

Explain why bats can ascertain distances, directions, nature, and sizes of the obstacles without any “eyes”.

A person is standing on a rotating table with metal spheres in his hands. If he withdraw his hands to his chest, what will be the effect on his angular velocity?

If each square metre of sun's surface, radiates energy at the rate of 6.3 × 10⁷J/ m²/ s and the Stefan's constant is 5.669 × 10^-8W/ m²/ k⁴. Calculate the temperature of the sun's energy assuming Stefan's Law applies to the sun's rediation.

Name the device used for measuring the mass of atoms and molecules.

A bird is tossing (flying to and fro) between two cars moving towards each other on a straight road. One car has a speed of 18m/h while the other has the speed of 27km/h. The bird starts moving from first car towards the other and is moving with the speed of 36km/h and when the two cars were separted by 36km. What is the total distance covered by the bird? What is the total displacement of the bird?