# Physics Notes for High School

DEDICATED TO HELP STUDENTS EXCEL IN PHYSICS BY GIVING NOTES, MOTIVATION AND RESOURCES ESPECIALLY FOR (O-LEVEL), High School, Secondary School Students. Grade 9 | Grade 10 | Year 9 | Year 10 | Form 4 | Form 5| | This site is best seen using Web version. If this site helps, please consider sharing this in your social media. Thanks heaps! |

## 2020-06-09

### Effects of Forces

## 2020-05-25

### Application for the principles of momentum conservation

1.
Billiard / Pool game

Billiards game uses a ball to hit
other balls into holes. The more momentum the cue ball has the greater the
momentum force exerted on the target ball / balls.

2.
Water hose

Water that jets out from a
firemen hose exerts high backward force, hence firemen needs to hold fast the
hose to prevent it from moving.

3.
Boat

When rowing a boat, the backward
force exerted by the rower will result in the same forward force being
produced.

4.
Jet engine

The hot gas and vapour ejected at
the exhaust of a jet engine will produce an upward and forward force, equal to
the force exerted by the hot gas.

5.
Rocket

A mixture of oxygen and hydrogen
are burned up in the combustion chamber. This creates a very high pressure and
force which is expelled at the bottom of the rocket. As a result, an upward
force of similar magnitude is produced.

## 2020-05-15

### Linear momentum collision problem calculations 2

Questions

1. A
toy truck with a mass of 3 kg was moving at 3 ms^{-1} and hit with
another toy truck of 1 kg and was moving with a velocity of 1 ms^{-1},
in the opposite direction. After collision, both trucks moved together in the
same direction, calculate the common velocity of the two objects after
collision.

m

_{1}u_{1 }+ m_{2}u_{2 = (}m_{1}+ m_{2)}v(3)(3) + (1)(-1) = (3+1)v

9 – 1 = 4v

v = 2 ms

^{-1}

2.
A hunter shot a 100g
bullet from a 1.5kg gun. If the bullet travelled 200 ms-1 after being
triggered, what is the backward jerk of the gun. (Think final backward velocity
of the gun).

Total initial momentum = Total final momentum = 0

m

_{1}u_{1 }+ m_{2}u_{2 = }01.5(v) + 0.1(200) = 0 ß make sure to convert 100g to kg

1.5v +20 = 0

v = - 13.3 ms-1 ß Value is negative because gun moved in opposite direction

3.
A trolley of mass
2 kg was in a stationary condition, before a 5 g sticky plasticine was thrown
into it with a velocity of 500 ms-1. After hitting the trolley, the plasticine
sticks into it. Calculate the final velocity of both the trolley and
plasticine?

Use the classic formula of momentum conservation

m

_{1}u_{1 }+ m_{2}u_{2 }= m_{1}v_{1 }+ m_{2}v_{2}0.005 (500) + 2 (0) = (0.005+ 2)v

2.5 = 2.005v

v = 1.245 ms

^{-1 }