4Horizontal forces acting on a moving car thrust( force of the engine) drag( air resistance)
5Forces acting on an aeroplane lift, drag, gravity, thrust L=W and T=D when the plane is flying at a constant velocity
6First Law of Motion: Balanced Forces balanced forces = no change in velocity A stationary object will never move as long as the forces acting on it are balanced.
7Resultant force gives direction of acceleration The forces acting on an object moving at a constant velocity(steady speed) are also balanced forces.If the object starts to accelerate or decelerate then the forces will no longer be equal or balanced.
8What is happening to the helicopter in each picture?
9Thrust equals weight. Helicopter hovers at a constant altitude. Weight greater than thrust. Helicopter stays on the helipad or drops in altitude.Thrust is greater than weight. Helicopter takes off and increases in altitude.