Physics lord

27/11/2023

15/11/2023

LESSON NOTE ON WORK , ENERGY RGY AND POWER IN PHYSICS.

WORK

Work is said to be done whenever a force moves a body through a certain distance in the direction of force.

Work done can be defined mathematically as the product of the force and the displacement.

It is a scalar quantity & measured in Joules
W = F X d .........1. But F=mg
W = mgh ......... 2.

If a force is applied on a body at an angle Ø to the horizontal
Work done to move the body on the horizontal plane = Fcos Ø x d .............3.

Work done to raise the body to an appreciable height = Fcos Ø x d....... 4.

Examples- A boy of mass 50kg runs up a set of steps of total height 3.0m. Find the work done against gravity.

Solution
m = 50kg, h = 3m, g = 10m/s²
Work done = mgh
= 50 x 10 x 3
= 1500 Joules

Energy
Energy is defined as the ability to do work. It is a scalar quantity & measured in Joules. There are many forms of energy.

These include:
1. Mechanical energy
2. Thermal energy
3. Chemical energy
4. Electrical energy
5. Nuclear/Atomic Energy
6. Solar/Light energy
7. Sound Energy

Types of Mechanical Energy.

Mechanical energy is classified as
1. Potential energy
2. Kinetic energy

POTENTIAL ENERGY:- is simply stored energy i.e. energy possessed by a body by virtue of its states:
P.E = mgh ........5.

KINETIC ENERGY: is the energy possessed by a body by virtue of its motion.

Examples area student running a race, wind or air motion, electrical charges in motion, a moving bullet
K.E = ½ mv²........6.

Example - An object of mass 5kg is moving at a constant velocity of 15mls. Calculate its kinetic energy.

Solution:
K.E = ½ mv² = ½ x 5 x 15 x 15 = 562.5 J

Example - Find the potential energy of a boy of mass 10kg standing on a building floor 10m above the ground level.
g = 10m/s²
Solution:
P.E =mgh = 10 x 10 x10 =1000 J

POWER
Power is defined as the rate of doing work or the rate of transfer of energy.

It is a scalar quantity & measured in watt
Power = work done/time

26/10/2023

SOME EQUATIONS INVOLVING PROJECTILE MOTION
Below are a couple of important equations related to projectile motion:

1. HORIZONTAL DISTANCE (range) of a projectile:
Range = (Initial velocity × Time of flight) × cos(θ)
θ represents the launch angle of the projectile.

2. VERTICAL DISPLACEMENT OF A PROJECTILE:
Displacement = (Initial velocity × Time) ×sin(θ) - (0.5 × g × Time^2)
g represents the acceleration due to gravity (approximately 9.8 m/s². or 10m/s²).

These equations help calculate the horizontal distance covered by a projectile and its vertical displacement at any given time during its flight. They take into account the initial velocity, launch angle, time, and the effect of gravity.

21/10/2023

RECOIL OF A BULLET
When a gun is fired, it releases a bullet by igniting gunpowder inside the cartridge. This process creates a high-pressure gas that propels the bullet forward. But, according to Newton's third law of motion, for every action, there is an equal and opposite reaction. So, when the bullet is propelled forward with a force, an equal force is exerted in the opposite direction, causing the gun to recoil backward.

The recoil of a gun is a result of conservation of momentum. The momentum of the bullet and the gun must be equal and opposite to each other. The gun's mass is much larger than the bullet's mass, so the gun moves backward with less speed but greater force compared to the bullet. The force of the recoil can be felt by the shooter as a backward kick or push.

To manage recoil, guns are designed with features like recoil-absorbing stocks or grips, muzzle brakes, and recoil pads. These features help distribute and reduce the force of the recoil, making it more manageable for the shooter.

Remember, safety is always crucial when handling fi****ms. Proper training, following safety guidelines, and using protective gear are essential for a safe shooting experience.
Ofurum Francis
Everyone

28/09/2023

As speed of light is too slow 😀 . If we see large distance 🙀.

27/09/2023

Projectile is any object that is lunched into the air at an angle and allowed to move freely under gravity.
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24/08/2023

Did you know
1. Isaac Newton invented calculator
2. The two places you can see from the moon is the Rift valley and great wall of China.
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26/07/2023

18/07/2023

Did you know
Birds requires gravity to swallow
Birds cannot chew their food and instead swallow their prey whole. The esophagus of a bird is wide enough to swallow larger meals. They depend on gravity to push their food down the esophagus and then later propelled into their stomach. This is one of the importance of gravity so without gravity birds cannot feed and without feeding the can't survive.

24/06/2023

NEWTON'S LAW OF MOTION
1. A body at rest or constant motion will continue to be at rest or motion unless it is acted upon by an external influence called force.
2. The acceleration of the body is directly proportional to the force acting on it and inversly proportional to its mass
That is A=F×M.
3. For every action there is an equal and opposite reaction.

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16/06/2023

FIELDS
Field is a space or a region under the influence of some physical agency such as gravitational field, magnetic field,electric field,etc.
Classes of force field
1.scalar force field
2.vector force field
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04/06/2023

LED means light emitting diodes follow page to learn more

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