A lorry of mass $$$16000 \mathrm{~kg}$$$ is travelling along a straight horizontal road. The engine of the lorry is working at constant power. The work done by the driving force in $$$10 \mathrm{~s}$$$ is $$$750000 \mathrm{~J}$$$. There is a constant resistance force acting on the lorry of magnitude $$$2400 \mathrm{~N}$$$. Find the acceleration of the lorry at an instant when its speed is $$$25 \mathrm{~m} \mathrm{~s}^{-1}$$$. .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

Mathematics

IGCSE&ALevel

CAIE

Exam No：9709_m20_qp_42 Year：2020 Question No：1(b)

Answer:

Driving force $\mathrm{DF}=75000 / 25$
$[\mathrm{DF}-2400=16000 a]$
$a=0.0375 \mathrm{~ms}^{-2}$

Knowledge points:

4.5.4 use the definition of power as the rate at which a force does work, and use the relationship between power, force and velocity for a force acting in the direction of motion Including calculation of (average) power;P = Fv

4.5.5 solve problems involving, for example, the instantaneous acceleration of a car moving on a hill

Answer:

Knowledge points:

Solution:

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