The diagram shows the forces acting on a lorry as it travels along a flat road. Two of the forces have effects that cancel each other out. Which two? Explain your answer.

The forces B and D gave equal force vectors but in opposite directions. The resultant force between B and D will be 0 , as the forces will be “cancelling” or balancing each other. When two or more forces act on an object, the resultant force can be found by adding up the individual forces.

The diagram shows the forces acting on a lorry as it travels along a flat road. What is the resultant force acting on the lorry? Give its magnitude and direction.

A resultant force is the force (magnitude and direction) obtained when two or more forces are combined. The resultant force is given as: F o r c e = R e s u l t a n t f o r c e o f B a n d D + R e s u l t a n t f o r c e o f A a n d C F o r c e = B - D + A - C F o r c e = 5000 - 5000 + 1300 - 1200 F o r c e = 100 N The magnitude of the resultant force is 100 N in the A direction. That is the lorry will move in forward direction.

The diagram shows the forces acting on a lorry as it travels along a flat road. What effect will this resultant force have on the speed at which the lorry is travelling?

Force is a vector quantity. We know that to change the state of motion of a body, we should apply an external unbalanced force. The unbalanced force to the left or the force in direction A will steadily increase the speed (accelerate) of the lorry to the left, and it causes the motion.