Physics
(a) A runner of mass 60 kg runs upstairs and reaches the 10 m high first floor in 4 s.
Calculate the
I. force of gravity acting on him
II. work done by him against gravity and
III. power developed by the runner.
(b) Give two examples in which mechanical energy is conserved.
Related Questions
(a) A force applied on a
I. rigid body
II. non-rigid body
How does the effect of force differ in the two cases?
(b) Give one example of couple force.
(a) In a single movable pulley, if the weight of the load is L and the weight of the movable pulley is w, find out the expression for its mechanical advantage.
(b) Which simple machine is used by labourers to load heavy barrels on a truck?
(c) Does a single fixed pulley help us to multiple force? In what way is it useful?
Kunal and Abhimanyu were waiting to go cross a railway crossing. Kunal jumped over the barrier and curiously put his ear on the railway track. Abhimanyu opposed Kunal and pulled him away from the railway track.
(a) Why did Kunal put his ear on the railway track?
(b) Why did Abhimanyu pull Kunal away from the railway track?
(c) Name the waves used for sound ranging. State one reason for their use.
A mixture of radio active substance gives off three types of radiations.
I. Name the radiation which travels with the speed of light.
II. Name the radiation which has the highest ionising power.
III. Name the radiation which is negatively charged.
(b) When an alpha particle gains two elections, it becomes neutral and an atom of an element which is a rare gas. Name this rare gas.