FORCE, MASS AND ACCELERATION
4 marks · NormalA student pulls a cart of mass 8.0 kg along a smooth surface. The cart accelerates at 2.5 m/s^2.
State the equation linking force, mass, and acceleration.
Calculate the unbalanced force applied to the cart.
Explain what would happen to the acceleration if the mass of the cart was halved, assuming the same force is applied.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) F = m x a
(b) 20 N
(c) Acceleration doubles (it increases, since acceleration is inversely proportional to mass for the same force)
Common mistakes: Omitting units for force; Reversing cause/effect for mass and acceleration
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States correct equation F = m x a.
M1 (b) · 1 mark · Substitutes values for m and a correctly. (follow-through)
A1 (b) · 1 mark · Obtains correct answer (20 N) with unit. (follow-through)
B2 (c) · 1 mark · Correctly states that acceleration doubles or increases (inverse proportionality).
Worked solution
a) The equation is:
b) Substitute the values into the equation:
c) If the mass is halved, the acceleration will double for the same force, because acceleration is inversely proportional to mass.