6 (a) The magnitude and direction of a force can be represented by a vector - Edexcel - GCSE Physics Combined Science - Question 6 - 2020 - Paper 1

In this scenario, the wooden block is moving at a constant horizontal velocity, indicating that the net force acting on it is zero. The analysis can be divided into horizontal and vertical forces:

Horizontal Forces

• Tension in the String: The tension in the string provides a horizontal force acting to pull the wooden block across the table. This tension is one of the key horizontal forces.

• Friction Between the Table and the Block: The frictional force arises due to contact between the block and the table and acts opposite to the direction of motion. It resists the motion of the block. In this case, the tension from the string balances the frictional force, resulting in no net force:

  The force due to friction is equal to the tension in the string, keeping the block moving at a constant velocity.

Vertical Forces

• Normal Reaction Force: The table exerts an upward normal force on the block, which counteracts the block's weight. This normal force balances the weight of the block, ensuring it does not accelerate vertically. Thus, the forces in the vertical direction are also equal and opposite:
  • Weight of the block acts downward due to gravity.
  • Normal force acts upward from the table.

Overall, since there is no net force acting on the block in both the horizontal and vertical directions, it continues to move across the table at a constant horizontal velocity.