On a straight horizontal test track, driverless vehicles (with no passengers) are being tested. A car of mass $$$1600 \mathrm{~kg}$$$ is towing a trailer of mass $$$700 \mathrm{~kg}$$$ along the track. The brakes are applied, resulting in a deceleration of $$$12 \mathrm{~m} \mathrm{~s}^{-2}$$$. The braking force acts on the car only. In addition to the braking force there are constant resistance forces of $$$600 \mathrm{~N}$$$ on the car and of $$$200 \mathrm{~N}$$$ on the trailer. Find the braking force. .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

Mathematics

IGCSE&ALevel

CAIE

Exam No：9709_m20_qp_42 Year：2020 Question No：6(b)

Answer:

Car $\quad[T-F-600=1600 \times-12]$
or
System $[-600-200-F=2300 \times-12]$
Braking force $F=26800 \mathrm{~N}$

Knowledge points:

4.4.1 apply Newton’s laws of motion to the linear motion of a particle of constant mass moving under the action of constant forces, which may include friction, tension in an inextensible string and thrust in a connecting rod If any other forces resisting motion are to be considered (e.g. air resistance) this will be indicated in the question.

4.4.4 solve simple problems which may be modelled as the motion of connected particles. e.g. particles connected by a light inextensible string passing over a smooth pulley, or a car towing a trailer by means of either a light rope or a light rigid tow- bar.

Answer:

Knowledge points:

Solution:

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