- When an object of height 4cm is placed at 40cm from a mirror the mirror forms the image on the object itself. If the height of the image is equal to the height of the object. Find out the focal

## The problem of a rock thrown vertically up

A rock is thrown vertically upward from the ground with an initial speed 15m/s. a. how high does it go b. how much time is required for the rock to reach its maximum height? c. what is the rock’s height at t=2.00s? (Posted by Merhawi) Answer: (a) u=15m/s a=-10m/s2 v=0 m/s [...]

## A Numerical from Combination of thin lenses in contact

Two thin lenses of focal lengths f1=20cm and f2=60cm are placed in contact. find the focal length f3 of the combined lenses. find also the focal length f of a third lens placed in contact with these two that would result in overall focal length f11=-40cm. (Asked Young) Incoming search terms:class 9 science sample paper for [...]

## A Numerical Problem from Mechanics

A rock explodes and is split into three pieces. two of them moves in direction of perpendicular to each other. One piece of mass 1kg moves with velocity of 5m/s and second piece of mass 2kg moves with velocity of 13m/s. find mass of third piece. (Tayade Kishore S asked) Incoming search terms:numerical problems [...]

## Numerical Problems based on Newton’s Laws

1.A machine gun has a mass of 20 kg. it fires 30g bullets at the rate of 400 bullets per second with a speed of 400 m/s. what force must be applied to the gun to keep it in position?

2.A ball