Unit 3: How do fields explain motion and electricity?
10 dot points across 3 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.
How do physicists explain motion in two dimensions?
- model the force vectors acting on an object on a banked track moving in uniform circular motion in a horizontal plane and identify the design speed at which friction is not required to keep the object on the track
A focused answer to the VCE Physics Unit 3 dot point on banked tracks. Covers the free-body diagram of a car on a banked curve, the derivation of the design speed at which no friction is needed ($\\tan\\theta = v^2 / rg$), and the worked example for a typical motorway off-ramp.
7 min answer → - investigate and analyse theoretically and practically the uniform circular motion of an object moving in a horizontal plane and on a vertical circle, including a quantitative analysis of the forces acting at the top and bottom of the vertical circle
A focused answer to the VCE Physics Unit 3 dot point on circular motion. Covers centripetal acceleration and force, the period-speed-radius relationships, the conical pendulum on a horizontal circle, and the forces at the top and bottom of a vertical loop (roller coasters, buckets of water, balls on strings).
9 min answer → - investigate and apply theoretically and practically Newton's three laws of motion in situations where two or more coplanar forces act along a straight line and in two dimensions; apply the concepts of momentum and impulse, including the conservation of momentum in one and two dimensions, and distinguish between elastic and inelastic collisions
A focused answer to the VCE Physics Unit 3 dot point on Newton's laws, momentum and impulse. Covers force, mass and acceleration in two dimensions, impulse as the area under a force-time graph, conservation of momentum in 1D and 2D collisions, and how to tell elastic from inelastic collisions.
9 min answer → - investigate and analyse theoretically and practically the motion of projectiles near Earth's surface including a qualitative description of the effects of air resistance
A focused answer to the VCE Physics Unit 3 dot point on projectile motion. Covers resolving the launch velocity into independent horizontal and vertical components, applying constant-velocity equations horizontally and SUVAT vertically with $g = 9.8$ m/s squared, the standard worked range and maximum height example, and a qualitative treatment of air resistance.
7 min answer →
How do things move without contact?
- describe electric fields using the field model, apply Coulomb's law $F = k q_1 q_2 / r^2$ and the relationships $E = F/q$, $E = kQ/r^2$ for point charges and $E = V/d$ for the uniform field between parallel plates; identify the directions of field, force and acceleration of charged particles in uniform and radial fields
A focused answer to the VCE Physics Unit 3 dot point on electric fields. Covers the field model, Coulomb's law for point charges, the radial field $E = kQ/r^2$, the uniform field between parallel plates $E = V/d$, the force and acceleration on a charged particle in each, and the conventional directions used by VCAA.
9 min answer → - describe gravitation using a field model and apply Newton's law of universal gravitation $F = G m_1 m_2 / r^2$ and the relationships $g = G M / r^2$, $g = F/m$, the work done by a gravitational field $W = \Delta U = mg \Delta h$ in a uniform field and the change in gravitational potential energy in non-uniform fields as the area under a force-distance graph
A focused answer to the VCE Physics Unit 3 dot point on gravitational fields. Covers the field model and field lines, Newton's law of universal gravitation, the equivalence of $g$ as field strength and as acceleration, gravitational potential energy in uniform and non-uniform fields, and how to read change in $U$ as the area under a $F$ vs $r$ graph.
10 min answer → - describe magnetic fields around magnets, current-carrying wires and solenoids; apply the right-hand rule to determine the directions of fields and forces; apply $F = qvB$ for a charged particle moving perpendicular to a uniform magnetic field, including circular motion of the particle
A focused answer to the VCE Physics Unit 3 dot point on magnetic fields. Covers field shapes around bar magnets, straight wires and solenoids, the right-hand grip and slap rules, the force on a moving charge ($F = qvB$), and the resulting circular motion of a charged particle in a uniform field.
9 min answer →
How are fields used in electricity generation?
- investigate and apply theoretically and practically electromagnetic induction using the concepts of magnetic flux $\Phi_B = B_\perp A$, induced EMF $\varepsilon = -N \Delta\Phi_B / \Delta t$ (Faraday's law) and Lenz's law to determine the direction of the induced current
A focused answer to the VCE Physics Unit 3 dot point on electromagnetic induction. Covers magnetic flux $\\Phi_B = B_\\perp A$, Faraday's law for the induced EMF, Lenz's law for the direction of the induced current, and the standard worked example of a bar magnet falling through a coil.
9 min answer → - explain the operation of AC and DC generators, distinguish between peak and RMS values of voltage and current using $V_{RMS} = V_{peak} / \sqrt{2}$ and $I_{RMS} = I_{peak} / \sqrt{2}$, and apply the ideal transformer relationship $V_1 / V_2 = N_1 / N_2 = I_2 / I_1$ to AC power transmission, including resistive losses $P_{loss} = I^2 R$
A focused answer to the VCE Physics Unit 3 dot point on AC and DC generators, RMS values and the ideal transformer. Covers slip rings vs split-ring commutators, the sinusoidal EMF from a rotating coil, the relationship between peak and RMS quantities, and why power is transmitted at high voltage to minimise $I^2 R$ losses.
10 min answer → - investigate and analyse theoretically and practically the force on a current-carrying conductor in a magnetic field, $F = n B I L$, and apply this to the operation of a simple DC motor including the role of the split-ring commutator
A focused answer to the VCE Physics Unit 3 dot point on the force on a current-carrying conductor in a magnetic field. Covers $F = n B I L$, the right-hand slap rule, the torque on a current loop, and the operation of a simple DC motor including the role of the split-ring commutator in keeping the rotation in one direction.
9 min answer →