Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic P1.6.2 — Work (Part (a))
• Topic P1.5.3 — Centre of gravity (Part (b))
• Topic P4.5.4 — Force on a current-carrying conductor (Part (c))
• Topic P5.2.2 — The three types of nuclear emission (Part (d))
(a) 125 kg
Work done against gravity is \(W = mgh\), so \(m = \dfrac{W}{gh}\).
\(m = \dfrac{2750}{10 \times 2.2} = \dfrac{2750}{22} = 125\,\text{kg}\).
(b) lower centre of mass
Lowering the crate lowers the overall centre of mass of the forklift truck system.
A lower centre of mass increases stability, since a larger tilt is needed before the line of action of weight moves outside the base, reducing the tendency to topple.
(c)(i) X: force upwards; Z: force downwards
Using Fleming’s left-hand rule with current and the magnetic field direction shown, the force on X acts upwards and the force on Z acts downwards.
These opposite forces on either side of the coil create the turning effect (torque) that rotates the motor.
(c)(ii) current is parallel to the magnetic field at Y
A force is only produced when current flows at an angle to the magnetic field.
At point Y, the current direction is parallel to the field lines, so no force acts on it.
(d)(i) it is a charged particle
A β-particle is a fast-moving electron and therefore carries a (negative) electric charge.
A charged particle moving through a magnetic field experiences a force (the motor effect), which deflects its path.
(d)(ii) opposite direction, smaller deflection
An α-particle carries a positive charge, opposite to the negative charge of a β-particle, so it deflects in the opposite direction.
Because an α-particle has a much greater mass than a β-particle, it deflects less for the same force.
