NSAA 2019 Physics S1

A builder lifts bags of cement onto the back of a lorry. Each bag has a mass of 25 kg. It takes the builder 2.5 minutes to load ten bags.

[diagram not to scale]

What are the total work done, T, on the ten bags and the average power required for T?

(gravitational field strength = $10 \text{Nkg}^{-1}$)

• A.total work done T/J: 375, average power / W: 2.5
• B.total work done T/J: 375, average power / W: 150
• C.total work done T/J: 625, average power / W: 4.2
• D.total work done T/J: 625, average power / W: 250
• E.total work done T/J: 3750, average power / W: 25
• F.total work done T/J: 3750, average power / W: 1500
• G.total work done T/J: 6250, average power / W: 42
• H.total work done T/J: 6250, average power / W: 2500

Answer: E

The current-voltage graph for a diode is shown.

The diode is connected in series with a resistor and a 6.0 V battery. The current in the circuit is 8.0 mA.

What is the resistance of the resistor?

(Assume that the battery has negligible resistance.)

• A.$0.15 \Omega$
• B.$0.60 \Omega$
• C.$0.75 \Omega$
• D.$4.8 \Omega$
• E.$150 \Omega$
• F.$600 \Omega$
• G.$750 \Omega$

Answer: F

• A.speed of P / speed of Q: 1.0, frequency of P / frequency of Q: $1.0 \times 10^{-8}$, nature of P: microwave, nature of Q: X-ray
• B.speed of P / speed of Q: 1.0, frequency of P / frequency of Q: $1.0 \times 10^{-8}$, nature of P: microwave, nature of Q: radio wave
• C.speed of P / speed of Q: 1.0, frequency of P / frequency of Q: $1.0 \times 10^8$, nature of P: infrared, nature of Q: ultraviolet
• D.speed of P / speed of Q: 1.0, frequency of P / frequency of Q: $1.0 \times 10^8$, nature of P: visible light, nature of Q: infrared
• E.speed of P / speed of Q: $1.0 \times 10^8$, frequency of P / frequency of Q: 1.0, nature of P: gamma, nature of Q: X-ray
• F.speed of P / speed of Q: $1.0 \times 10^8$, frequency of P / frequency of Q: 1.0, nature of P: gamma, nature of Q: infrared
• G.speed of P / speed of Q: $1.0 \times 10^8$, frequency of P / frequency of Q: $1.0 \times 10^{16}$, nature of P: infrared, nature of Q: radio wave
• H.speed of P / speed of Q: $1.0 \times 10^8$, frequency of P / frequency of Q: $1.0 \times 10^{16}$, nature of P: visible light, nature of Q: ultraviolet

Answer: A

• A.$27 \text{°C}$
• B.$39 \text{°C}$
• C.$54 \text{°C}$
• D.$75 \text{°C}$
• E.$96 \text{°C}$

Answer: C

• A.none of them
• B.1 only
• C.2 only
• D.3 only
• E.1 and 2 only
• F.1 and 3 only
• G.2 and 3 only
• H.1, 2 and 3

Answer: D

• A.40 m
• B.50 m
• C.60 m
• D.400 m
• E.500 m
• F.600 m

Answer: A

• A.60 W
• B.300 W
• C.6000 W
• D.24000 W
• E.120000 W
• F.9600000 W

Answer: A

Heat is supplied to an initially solid substance at a rate of 60 W.

The graph shows the variation of the temperature of the substance with time.

What is the mass of the substance?

(specific latent heat of fusion of substance = $100 \text{Jg}^{-1}$; assume that there is no heat transferred to the surroundings)

• A.0.013 g
• B.0.60 g
• C.3.0 g
• D.9.0 g
• E.27 g
• F.36 g

Answer: E

Two tanks of water are connected by a solid cylindrical copper bar of length l and diameter d.

The bar is insulated.

One tank contains water at $90 \text{°C}$ and the other tank contains water at temperature $\theta$.

For which of the following conditions is thermal energy conducted along the bar at the lowest rate?

• A.l/m: 0.40, d/cm: 4.0, $\theta$/°C: 20
• B.l/m: 0.40, d/cm: 4.0, $\theta$/°C: 40
• C.l/m: 0.40, d/cm: 8.0, $\theta$/°C: 20
• D.l/m: 0.40, d/cm: 8.0, $\theta$/°C: 40
• E.l/m: 0.80, d/cm: 4.0, $\theta$/°C: 20
• F.l/m: 0.80, d/cm: 4.0, $\theta$/°C: 40
• G.l/m: 0.80, d/cm: 8.0, $\theta$/°C: 20
• H.l/m: 0.80, d/cm: 8.0, $\theta$/°C: 40

Answer: F

• A.0.020 T
• B.0.040 T
• C.0.20 T
• D.0.40 T
• E.200 T
• F.400 T

Answer: C

• A.atomic number of Y: Z - 2, mass number of Y: A - 12
• B.atomic number of Y: Z - 5, mass number of Y: A - 8
• C.atomic number of Y: Z - 8, mass number of Y: A - 20
• D.atomic number of Y: Z - 10, mass number of Y: A - 24
• E.atomic number of Y: Z - 11, mass number of Y: A - 16

Answer: C

• A.2.0 N
• B.4.0 N
• C.8.0 N
• D.24 N
• E.28 N
• F.56 N

Answer: C

In the following circuit, all five resistors have the same resistance.

The reading on the voltmeter is 1.0 V.

What is the voltage across the battery?

• A.4.0 V
• B.5.0 V
• C.6.0 V
• D.7.0 V
• E.8.0 V
• F.9.0 V
• G.10 V

Answer: E

Two hovercraft travel horizontally in opposite directions along the same straight line. The mass and speed of each hovercraft are shown in the diagram. Horizontal resistive forces acting on each hovercraft are negligible.

The hovercraft collide and stick together. The collision lasts for 0.10 s.

Just before the collision, what is the total kinetic energy and the magnitude of the total momentum of the two hovercraft, and what is the magnitude of the average force acting horizontally on each hovercraft during the collision?

• A.total initial kinetic energy/kJ: 100, total initial momentum /kgms⁻¹: 0, average force on each hovercraft /kN: 2.0
• B.total initial kinetic energy/kJ: 100, total initial momentum /kgms⁻¹: 0, average force on each hovercraft /kN: 200
• C.total initial kinetic energy/kJ: 100, total initial momentum /kgms⁻¹: $4.0 \times 10^4$, average force on each hovercraft /kN: 2.0
• D.total initial kinetic energy/kJ: 100, total initial momentum /kgms⁻¹: $4.0 \times 10^4$, average force on each hovercraft /kN: 200
• E.total initial kinetic energy/kJ: 300, total initial momentum /kgms⁻¹: 0, average force on each hovercraft /kN: 2.0
• F.total initial kinetic energy/kJ: 300, total initial momentum /kgms⁻¹: 0, average force on each hovercraft /kN: 200
• G.total initial kinetic energy/kJ: 300, total initial momentum /kgms⁻¹: $4.0 \times 10^4$, average force on each hovercraft /kN: 2.0
• H.total initial kinetic energy/kJ: 300, total initial momentum /kgms⁻¹: $4.0 \times 10^4$, average force on each hovercraft /kN: 200

Answer: F

The graph shows how a car's velocity changes in 85 seconds.

What proportion of the total distance is travelled at constant velocity?

• A.$\frac{5}{29}$
• B.$\frac{5}{17}$
• C.$\frac{12}{17}$
• D.$\frac{24}{29}$
• E.$\frac{8}{9}$
• F.$\frac{16}{17}$

Answer: D

A block is designed with a cylindrical channel to accommodate a hot-water pipe. The block is 100 cm long and it has a square cross-section of side 22.0 cm with a cylindrical hole in the middle, as shown in the diagram:

[diagram not to scale]

The diameter of the cylindrical hole is 14.0 cm and the density of the material from which the block is made is $0.100 \text{g cm}^{-3}$.

What is the mass of the block?

(take $\pi$ to be $\frac{22}{7}$)

• A.1.32 kg
• B.3.30 kg
• C.13.2 kg
• D.33.0 kg
• E.132 kg
• F.330 kg
• G.1320 kg
• H.3300 kg

Answer: B

• A.The sample contains only isotope Y.
• B.1:7
• C.1:4
• D.1:3
• E.7:4

Answer: B