Educerie · IB Diploma · Physics
Theme A — Topic test · mark scheme
One mark per distinct point. A substitution mark is available for a correct equation with correct values, even where the arithmetic then fails. Error carried forward (ECF) applies throughout. A final answer with no unit, or with the wrong unit, loses the accuracy mark.
1Projectile motion — 6 marks
(a) [1]
u_y = 20 sin 30° = 10.0 m s⁻¹ | 1 |
|---|
Using
cosgives 17.3 m s⁻¹ and scores 0.
(b) [2]
Correct method: s = ut + ½at² with s = 0, or t = 2u_y/g | 1 ECF from (a) |
|---|---|
2.04 s | 1 |
A very common error is halving:
t = u_y/g = 1.02 sis the time to the top, not the flight time. Award the method mark, not the answer mark.
(c) [2]
uₓ = 20 cos 30° = 17.3 m s⁻¹ and uses R = uₓ t | 1 ECF from (b) |
|---|---|
35.3 m (accept 35.2–35.4) | 1 |
Applying a suvat equation with acceleration to the horizontal motion scores 0 — there is no horizontal acceleration.
(d) [1]
| Air resistance is negligible or the ball is a point mass or g is constant over the flight or it lands at the launch height | 1 |
|---|
"The ball is thrown perfectly" and similar non-physical answers score 0.
2Collision — 6 marks
(a) [2]
Applies conservation of momentum: (2.0 × 3.0) + 0 = (2.0 + 3.0)v | 1 |
|---|---|
v = 1.2 m s⁻¹ | 1 |
Dividing by 2.0 or 3.0 rather than the combined 5.0 kg is the expected error.
(b) [3]
Calculates kinetic energy before: ½ × 2.0 × 3.0² = 9.0 J | 1 |
|---|---|
Calculates kinetic energy after: ½ × 5.0 × 1.2² = 3.6 J | 1 ECF from (a) |
| Concludes the collision is inelastic because kinetic energy is not conserved | 1 |
Determine requires both values on the page. A bare "inelastic, because they stick together" is a correct fact but does not answer the question as set — award 1 at most. Reject any argument based on momentum. Momentum is conserved in both collision types and so cannot distinguish them; such an answer scores 0 for the final mark.
(c) [1]
| Transferred to internal (thermal) energy and/or sound | 1 |
|---|
"It is lost" or "it disappears" scores 0 — energy is conserved overall.
3Inclined plane — 4 marks
(a) [2]
Uses mg sin θ, e.g. 5.0 × 9.81 × sin 25° | 1 |
|---|---|
20.7 N | 1 |
mg cos θ = 44.5 Nis the standard error and scores 0.
(b) [2]
Uses a = F/m with their (a), or a = g sin θ | 1 ECF from (a) |
|---|---|
4.15 m s⁻² (accept 4.1–4.2) | 1 |
Accept a comment that the acceleration is independent of mass, but it is not required. An answer of
9.81 m s⁻²(free fall) scores 0.
4Work, energy and power — 4 marks
(a) [2]
Uses Ek = ½mv², e.g. ½ × 1200 × 25² | 1 |
|---|---|
3.75 × 10⁵ J (accept 375 000 J or 375 kJ) | 1 |
A frequent error is
½mvwithout squaring, giving 15 000. Award the method mark only if the square is present.
(b) [2]
Uses P = W/t with their (a), e.g. 3.75 × 10⁵ / 8.0 | 1 ECF from (a) |
|---|---|
4.69 × 10⁴ W (accept 46 875 W or 46.9 kW) | 1 |
P = Fvusing the final velocity gives the instantaneous power at 8.0 s, not the average, and does not answer the question. Award 0 unless the average is also reached.
Mark distribution
| Split | Allocation |
|---|---|
| By sub-topic | A.1 Kinematics 6 · A.2 Forces and momentum 10 · A.3 Work, energy and power 4 |
| By objective | AO1 knowledge 2 · AO2 application 13 · AO3 analysis and evaluation 5 |
| By command term | Calculate 13 · Determine 3 · State 2 · (assumption) 1 · (energy fate) 1 |
Total: 20 marks
Educerie · original mark scheme for original questions, written against the published IB syllabus structure for Physics Theme A, first assessment 2025. Last reviewed 5 September 2026.