2023 · H1 Physics · Paper 1
2023 H1 Physics Paper 1, worked
30 multiple-choice questions · 30 marks
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Q1Answer C
Power is energy per unit time.
- J s and kJ min are energy divided by time, so they are units of power.
- kW is a unit of power.
- kW h is a power multiplied by a time, so it is a unit of energy, not power.
Q2Answer A
The volume of the stone is a difference, .
For a sum or a difference, the absolute uncertainties add (they never subtract):Percentage uncertainties are added only for products and quotients.
Q3Answer C
Speed is a scalar, so it has magnitude only. Acceleration, displacement and velocity are vectors, which have direction.
Q4Answer D
For constant acceleration,Compare with , where and : the intercept is and the gradient is .
Q5Answer D
The aeroplane starts from rest:
Q6Answer C
For isolated objects, momentum is conserved in every collision, and total energy is always conserved.
In an inelastic collision, some kinetic energy is converted into other forms (heat, sound, deformation), so kinetic energy is not conserved.
Q7Answer D
Speed just before impact (falling 3.0 m from rest):Speed just after the bounce (rising 2.0 m):Taking upwards as positive, the change in momentum is
Q8Answer B
The object is in equilibrium, so , and form a closed triangle with arrows head to tail.
- acts vertically downwards and horizontally to the right.
- acts along the string, upwards and to the left, at 30 to the vertical.
Because is at 30 to the vertical, , so the horizontal side of the triangle is shorter than the vertical side.
In B, points down, continues to the right from its head, and closes the triangle back up and to the left at 30 to the vertical. In D the arrows are head to tail, but is at about 60 to the vertical. In A and C, points downwards.
Q9Answer C
From the graph, the length increases from 5 cm to 30 cm when 400 g is added:
Q10Answer A
Take moments about the hinge at the wall.
The bar meets the shelf 20 cm from the wall, at 40 to the horizontal. Only the vertical component of its push has a moment about the hinge:The weight of the shelf (10 N) acts at its centre, 15 cm from the wall. The load is at X, 25 cm from the wall.
Q11Answer D
The object falls from rest with constant acceleration, so the distance fallen is proportional to . At time it has fallen of the height .
Its height above the ground is then :
Q12Answer A
An angle in radians is arc length divided by radius:
Q13Answer B
The centripetal force is provided by gravity:
Q14Answer D
The rock stays above the same point, so its period equals the length of the Martian day, s. Its orbital radius isGravity provides the centripetal force:At the surface ( m):
Q15Answer D
The satellite's direction of motion changes continuously, so its velocity is changing and it is accelerating. There is a resultant force on it (the gravitational force, towards the Earth), so it is not in equilibrium.
The gravitational force is the centripetal force. It is not balanced by a separate centripetal force, so B is wrong.
Q16Answer B
Q17Answer D
- A: , so
- B: , so
- C: , so
- D: , so
Q18Answer B
The charge passing per second is 43 C. Each electron carries C:The 12 V is not needed.
Q19Answer A
As decreases, the total resistance decreases, so the current increases: the ammeter reading increases.
The voltmeter measures the p.d. across , which is the terminal p.d., . A larger current means larger lost volts , so the voltmeter reading decreases.
Q20Answer C
To vary the p.d. across the lamp all the way from 0 to , the circuit must be a potential divider: a potentiometer connected across the whole battery, with the lamp connected between one end and the sliding contact.
In C, with the slider at one end the lamp has the full across it, and with the slider at the other end it has zero.
In A and B a fixed resistor is always in series with part of the circuit, so the lamp can never reach (or zero). D is a variable resistor in series with the lamp, which can reduce the p.d. but never to zero.
Q21Answer B
The terminal p.d. is 12 V, which is half the e.m.f., so the lost volts across the internal resistance are also 12 V. The external resistance must equal the internal resistance, 6.0 .
- Two 4.0 resistors give either 8.0 (series) or 2.0 (parallel).
- Three resistors: one in series with two in parallel gives .
The least number is 3.
Q22Answer A
From the graph, at 50 C the thermistor's resistance is 1.0 k.
The output is the p.d. across the thermistor. The 20.0 V is shared in the ratio of the resistances:
Q23Answer D
An α-particle has charge C.The gold nucleus is positive, so its field points away from it, to the right at X.
Q24Answer D
A magnetic field exerts a force only on a moving charge (). The charge is stationary, so the force is zero.
Q25Answer B
Parallel wires with currents in opposite directions repel. Y is pushed away from X, so the force on Y is to the right (direction B).
Q26Answer B
The force on the electron is perpendicular to its velocity.
- A magnetic force is perpendicular to both the velocity and the field. A field perpendicular to the velocity and to gives exactly this (B). A field along (A) would give a force perpendicular to , not along it.
- An electric force on an electron is along the field line (opposite to the field). For C, the force would be perpendicular to . For D, the force would be along the velocity, not at right angles to it.
Q27Answer B
In every valid equation, both the nucleon numbers and the proton numbers must balance.
- A: , ✓
- B: ✓, but ✗
- C: , ✓
- D: , ✓
(β-decay increases the proton number by 1, so lead cannot become thallium this way.)
Q28Answer B
An α-particle has 2 protons and 2 neutrons.
Q29Answer B
Only a very massive, concentrated positive charge can turn an α-particle back through more than 90, and the fact that only a small number did so shows that the nucleus is very small compared with the atom.
A shows that most of the atom is empty space, but not that there is a small massive nucleus. C and D are features of how the experiment is carried out.
Q30Answer A
Subtract the background count of 50 min to get the count rate due to the sample.
- At : min.
- Half of this is 100 min, which is a measured count of min. From the graph this occurs at s.
(Check: a quarter, 50 min, is a measured 100 min at s, one more half-life.)
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