(a) The acceleration of the sledge is 1.5 m/s2. The mass of the child and sledge is 38kg.
(i) State the equation linking force, mass and acceleration. [1]
(ii) Calculate the force needed to produce this acceleration. [2]
(iii) Suggest a reason why the force exerted on the sledge by the man must be greater than the force calculated.
Answers
Question:
(a) The acceleration of the sledge is 1.5 m/s². The mass of the child and sledge is 38kg.
. The mass of the child and sledge is 38kg.(i) State the equation linking force, mass and acceleration. [1]
Ans.
Newton's 2nd law states that the time rate of change of the momentum of a body is equal in both magnitude and direction to the force imposed on it.
Hence, equation linking force, mass and acceleration is:-
→ F = m*a
(ii) Calculate the force needed to produce this acceleration. [2]
Ans.
Since, F = m*a
∴ Required force = 38 × 1.5 = 57N
(iii) Suggest a reason why the force exerted on the sledge by the man must be greater than the force calculated.
Ans.
Yes, force exerted on the the sledge by the man must be greater because there's a frictional force acting between the sledge and the ground which creates a resistive force. Hence, to oppose the resistance and move the sledge the required force must be greater.