4 Horizontal forces acting on a moving car thrust( force of the engine) drag( air resistance)
5 Forces acting on an aeroplane lift, drag, gravity, thrust L=W and T=D when the plane is flying at a constant velocity
6 First 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.
7 Resultant 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.
8 What is happening to the helicopter in each picture?
9 Thrust 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.