CAIE M1 (Mechanics 1) 2019 June

2 A car moves in a straight line with initial speed \(u \mathrm {~m} \mathrm {~s} ^ { - 1 }\) and constant acceleration \(a \mathrm {~m} \mathrm {~s} ^ { - 2 }\). The car takes 5 s to travel the first 80 m and it takes 8 s to travel the first 160 m . Find \(a\) and \(u\).

3 A particle of mass 13 kg is on a rough plane inclined at an angle of \(\theta\) to the horizontal, where \(\tan \theta = \frac { 5 } { 12 }\). The coefficient of friction between the particle and the plane is 0.3 . A force of magnitude \(T \mathrm {~N}\), acting parallel to a line of greatest slope, moves the particle a distance of 2.5 m up the plane at a constant speed. Find the work done by this force.

4 A constant resistance to motion of magnitude 350 N acts on a car of mass 1250 kg . The engine of the car exerts a constant driving force of 1200 N . The car travels along a road inclined at an angle of \(\theta\) to the horizontal, where \(\sin \theta = 0.05\). Find the speed of the car when it has moved 100 m from rest in each of the following cases.

• The car is moving up the hill.
• The car is moving down the hill.
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Two particles \(A\) and \(B\), of masses 0.4 kg and 0.2 kg respectively, are connected by a light inextensible string which passes over a fixed smooth pulley. Both \(A\) and \(B\) are 0.5 m above the ground. The particles hang vertically (see diagram). The particles are released from rest. In the subsequent motion \(B\) does not reach the pulley and \(A\) remains at rest after reaching the ground.

1. For the motion before \(A\) reaches the ground, show that the magnitude of the acceleration of each particle is \(\frac { 10 } { 3 } \mathrm {~m} \mathrm {~s} ^ { - 2 }\) and find the tension in the string.
2. Find the maximum height of \(B\) above the ground.

6 A car has mass 1000 kg . When the car is travelling at a steady speed of \(v \mathrm {~m} \mathrm {~s} ^ { - 1 }\), where \(v > 2\), the resistance to motion of the car is \(( A v + B ) \mathrm { N }\), where \(A\) and \(B\) are constants. The car can travel along a horizontal road at a steady speed of \(18 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) when its engine is working at 36 kW . The car can travel up a hill inclined at an angle of \(\theta\) to the horizontal, where \(\sin \theta = 0.05\), at a steady speed of \(12 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) when its engine is working at 21 kW . Find \(A\) and \(B\).

7 Particles \(P\) and \(Q\) leave a fixed point \(A\) at the same time and travel in the same straight line. The velocity of \(P\) after \(t\) seconds is \(6 t ( t - 3 ) \mathrm { m } \mathrm { s } ^ { - 1 }\) and the velocity of \(Q\) after \(t\) seconds is \(( 10 - 2 t ) \mathrm { m } \mathrm { s } ^ { - 1 }\).

1. Sketch, on the same axes, velocity-time graphs for \(P\) and \(Q\) for \(0 \leqslant t \leqslant 5\).
2. Verify that \(P\) and \(Q\) meet after 5 seconds.
3. Find the greatest distance between \(P\) and \(Q\) for \(0 \leqslant t \leqslant 5\).
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