What are Forces? Module 3 What are forces? In module 2 we learned that a force is a push or a pull. We learned that Newton’s 2 nd Law states that a Force is equal to the mass of a moving object times its acceleration.
The rougher the surface and the stronger the force between the surfaces, the greater the amount of friction.
Gravitation force is equal to weight, therefore…
Weight = mass X 9.8 m/s2
Weight = 70.0 kg X 9.8 m/s2
Weight = 686 N
Remember that 1 N = (1 kg) (1m/s2)
When an object is thrown into the air, two forces and two motions affect the movement of the object.
The object may be thrown horizontally with a certain force, but the vertical force of gravity combines to affect the motion.
Slow projectile - shoot a monkey
Fast projectile - shoot a monkey
Two objects in contact with one another and moving must use the action-reaction law.
Rocket propulsion involves the action-reaction law. The explosion from one end of the rocket causes a force in that direction. This causes an unbalanced force in the opposite direction causing the rocket to accelerate. Video Clip!