Junior physics-Unbalanced forces

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The Tomcat pictured on the left is accelerating horizontally close to the surface of the water.

What forces are acting on this plane? Drag, thrust, gravity, lift.

What are the balanced forces? Since it is flying horizontal gravity and lift are equal and acting in th opposite direction.

What are the unbalanced forces? If it is accelerating unbalanced forces must be acting. Thrust is greater than drag so the plane accelerates forward.

What happens to the force of drag as the plane slows down? Drag forces depend on the speed of the plane. The faster a plane moves the greater the drag force acting on it.

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The skydiver is descending at a slow constant speed. The drag forces are maximised by the parachute and oppose the force of gravity pushing down.

In what direction are the drag and gravitational forces acting?
Gravity acts downwards while drag resists the downward motion of the paraglider.
Are they balanced?
Since the speed of descent is constant there is no net force acting on the paraglider. The forces acting on the paraglider are balanced.
What would happen if both of these forces were equal and acted in opposite directions?

The paraglider would fall at a constant speed.

Unbalanced Forces
A force is a push or a pull that causes an object to either: - increase or decrease its speed - change its direction - change its shape. If any of these things happen then a force must be acting on the object in question.
	This F111 Fighter plane is accelerating skywards. Since it is accelerating, its speed is increasing, a force must be acting on it. Click to find out more about acceleration. The forces acting on it include drag, lift, gravity and thrust. Obviously the plane is acted on by unbalanced forces. SInce the plane is climbing, the force of lift is greater than the force of gravity and thrust is greater than drag.
The racing car on the right accelerates along a horizontal road surface. Once again unblanced forces are acting on this vehicle. The force acting on this vehicle include drag, friction, thrust from the engine, gravity and the push upwards by the road surface. SInce the car accelerates the thrust produced by the engine is greater than the drag and friction forces acting on the vehicle. The road acts to push the car upwards with a force equal and opposite to the force of gravity pushing down.
	The Tomcat pictured on the left is accelerating horizontally close to the surface of the water. What forces are acting on this plane? What are the balanced forces? What are the unbalanced forces? What happens to the force of drag as the plane slows down? Solution
The skydiver is descending at a slow constant speed. The drag forces are maximised by the parachute and oppose the force of gravity pushing down. In what direction are the drag and gravitational forces acting? Are they balanced? What would happen if both of these forces were equal and acted in opposite directions? Solution
Click to see a 120kb movie of a goldfish swimming around in a bowl. Explain why it is obvious that unbalanced forces are acting