Is Matter Around Us Pure ? — Science STD 9 — Question

When is the work done by a force on a body: (a) positive, (b) negative, and (c) zero?

A weightlifter is lifting weights of mass 200kg up to a height of 2 metres. If g = 9.8ms^-2, Calculate:

1. Potential energy acquired by the weights.
2. Work done by the weightlifter.

Draw a diagrammatic sketch of oxygen cycle in nature.

1. An electric bell rings.
2. Someone speaks into a microphone.
3. There is a picture on a television screen.
4. A torch is on.

What is the difference between gravitational potential energy and elastic potential energy? Give one example of a body having gravitational potential energy and another having elastic potential energy.

Draw a flow chart showing classification of kingdom Plantae.