(a) Friction
(b) Newton's 3rd law states that for every action there is an equal and opposite reaction.
The tyre pushes against the ground so the ground pushes back against the tyre (friction) by an equal and opposite reaction.
(c) By Newton's third law the force is 4 X 1000N = 4000N
(d) An object accelerates
(i) in direct proportion to and
(ii) in the direction of a resultant force and
(iii) inversely proportional to its mass.
F = ma
(e) F = ma
a = ^{F}/_{m}
a = ^{4000N}/_{2000kg}
a = 2ms^{-2}.
(f) u = 0ms^{-1}
a = 2ms^{-2}
t = 20s
v = u + at
v =
0ms^{-1}+ (2ms^{-2}) (20s)
V =
40ms^{-1}
(f) There is no resultant (or net) force on the truck so by Newton's first law the velocity remains constant. |