Speed is distance travelled by an object per unit of time
speed=distance travelled / time
velocity is speed in a given direction; it therefore tells us two things about moving object: its speed and its direction
The rate of change of velocity is called acceleration. Acceleration refers to any change of velocity, either positive or negative.
acceleration= final velocity-original velocity / time
Momentum an object traveling at a specific velocity has quantity called momentum.
Momentum=mass x velocity
p = mv EX. p = (2.0 kg)(4.0 m/s); p = 8.0 kg-m/s
Newton's first law
The law of inertia, states that objects in motion tend to stay in motion and that object at rest tend to stay at rest.
Newton's 2 Laws
Newton’s second law describes the relationship between force, mass, and acceleration. It states that the force applied on an object equals the mass of the object times its acceleration.
Force= mass x acceleration (F=ma).
Newton's 3 Law
The third law states that for every force there is an equal and opposite force. For example, if you push on a wall, it will push back on you as hard as you are pushing on it. The blast from the back of the rockets pushes the rocket forward.
Density is a physical property of matter that is defined as the ratio of an object's mass to its volume.
Energy is ability to do work
Kinetic energy is energy associated with motion. Any moving body has this type energy because it is able to do work by moving other bodies.
Kinetic energy = ½(mass x velocity)2
Potential energy is the energy stored in a body because of its position
Work is defined as the product of the force applied to an object and the distance through which the force is applied. Work is the transfer of energy. Work has a specific definition in physics, it is equal to the force needed to move an object multiplied by the distance it moved.
Work = Force x Distance
How much work is done if a force of 20 N is used to displace an object 3 m? W = (20 N)(3 m)=60N-m. =60 Joules because 1 Joule is equal to 1 Newton-meter
A joule is the unit of energy equal to the work done by a force of 1 Newton acting over distance of 1 meter. One joule is the amount of energy it takes to lift an object that weighs one Newton a one meter distance.
Power is rate at which work is done. The power of a machine is the total work done divided by the same time taken. Since work equals force times distance, the formula power is:
Power = work/time
The six simple machines
The six simple machines are the lever, wedge, screw, inclines planes, wheel and axle, and pulley
An inclined plane is a simple machine. An inclined plane is a ramp used to reduce the effort needed to raise or lower an object over a vertical height.
A wedge (klin) is a moving inclined plane
A lever( richag) is a simple machine. A lever bar exerts a force to move a load by turning on a pivot or fulcrum
Pulley is a chain or rope wrapped around a wheel
A wheel and axle
A wheel and axle act as a lever that rotates in a circle
A screw is an inclined plane wrapped around a cylinder