PHYSICAL LAWS, WORK AND MOTION

PHYSICAL LAWS, WORK, & MOTION

Motion is a change in an object's position relative to time and a distant reference point. Motion is a part of all matter in the universe & is affected by forces, which are push or pull factors that change an object's speed or direction. [Speed refers to how fast an object moves. When an object travels equal distances in equal amounts of time, the object is traveling at a constant speed.

Speed=distance time

 Related to speed is the concept of momentum, which can be thought of as the amount of motion an object has or the power behind an object. An object's momentum is dependent on its mass & its velocity, which refers to both the direction & speed of an object, 

momentum = mass x velocity

acceleration is any change in velocity.

Gravity is the force that attracts any two objects toward each other. The strength of the gravitational pull depends on the masses of the two objects & the distance between them.

three laws of motion:

• The First Law - An object will remain at rest, or continue moving at the same speed and in the same direction unless an unbalanced force acts on the object. This is the law of inertia.

• The Second Law - If an object experiences an unbalanced force, it will accelerate. The acceleration depends on the magnitude of the force and the mass of an object.

• The Third Law - If object A exerts a force on object B, then B will exert an equal force on A, but in the opposite direction. Gun recoil is a good example of this. While the forces are ALWAYS equal, different masses cause different accelerations. Work occurs when a force moves an object in the direction of the force.

Work = force x distance

Power = work x time

Work occurs when a force moves an object in the direction of the force.

Power is the rate at which a certain amount of work is accomplished, & is measured in watts. One watt is the amount of power it takes to complete one joule of work in one second. Machines are implements that make work easier by redirecting or multiplying forces. Machines that complete work faster are said to have a mechanical advantage. There are six simple machines: Inclined plane, wedge, screw, lever, pulley, axle & wheel.