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A tow truck pulls a car along a gravel road.
The force applied by the engine of the tow truck is 9 000 N. The mass of the tow truck is 1 300 kg and the mass of the car is 950 kg. The vehicles are connected to each other by an inelastic tow bar of negligible mass.

The tow truck and car move at a CONSTANT VELOCITY.
1 Define the term frictional force.
2 NAME AND STATE the law that explains why the force exerted by the tow truck on the car is the same as the force exerted by the car on the tow truck.

If the coefficient of kinetic friction between the tow-truck tyres and the road surface is 0,45, calculate the:
3a Magnitude of the tension in the tow bar
b Coefficient of kinetic friction between the CAR tyres and the road surface
Suddenly the tow bar between the car and the tow truck disconnects and the car comes loose.
4 Using a relevant law of motion, explain why the car continues moving forward for a short distance.

5 Calculate the acceleration of the car as it comes to a stop after a short distance.
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1 Frictional force is the force that opposes the motion of an object and which acts parallel to the surface.

2 Newton's Third law: When object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A.

3a Fnet = ma
Fengine – f – T = 0
9 000 – 0,45(Fg) – T = 0
9 000– 0,45(1 300)(9,8) – T = 0
T = 3 267 N
b. Fnet = ma
T – f = 0
3 267 – f = 0
f = 3 267 N (backwards)
fk = μkN
fk = μkmg
3 267 = μk(950)(9,8)
μk = 0,35

4.  According to Newton's first law, an object will continue moving at a constant velocity unless a non-zero net force acts on it. The net force acting on the car now is the frictional force and it causes the car to slow down.

5. Fnet = ma
-3 267 = 950a
a = -3,44 m∙s-2
= 3,44 m∙s-2  backwards or to the right
by Silver Status (31.3k points)

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