NSAA 2016 Physics S1

Shortly after opening her parachute, a free-fall parachutist of mass 60 kg (including equipment) experiences the forces shown in the diagram.

drag (air resistance) = 900 N

[diagram not to scale]

weight = 600 N

Which line in the table gives the size and direction of the acceleration of the parachutist at this instant?

• A.size of acceleration/$ms^{-2}$: 5.0, direction of acceleration: downwards
• B.size of acceleration/$ms^{-2}$: 10.0, direction of acceleration: downwards
• C.size of acceleration/$ms^{-2}$: 5.0, direction of acceleration: upwards
• D.size of acceleration/$ms^{-2}$: 10.0, direction of acceleration: upwards
• E.size of acceleration/$ms^{-2}$: 0.0, direction of acceleration: -

Answer: C

The displacement/time graph shown represents a wave of wavelength 1.5 cm.

What is the speed of the wave?

• A.0.33 $cm s^{-1}$
• B.0.67 $cm s^{-1}$
• C.0.75 $cm s^{-1}$
• D.1.33 $cm s^{-1}$
• E.1.5 $cm s^{-1}$
• F.3.0 $cm s^{-1}$

Answer: C

• A.2 kg
• B.3 kg
• C.5 kg
• D.6 kg
• E.10 kg
• F.15 kg

Answer: B

• A.amp per ohm
• B.coulomb per joule
• C.joule per second
• D.newton per coulomb
• E.watt per amp

Answer: E

• A.25 Bq
• B.50 Bq
• C.55 Bq
• D.70 Bq
• E.100 Bq
• F.140 Bq

Answer: D

• A.10 m
• B.20 m
• C.50 m
• D.100 m
• E.200 m
• F.1000 m

Answer: B

A cyclist and a bike have a combined mass of 100 kg. The cyclist free-wheels (rolls without pedalling) at a constant speed of 0.80 $m s^{-1}$ down a slope where the cyclist descends 1.0 m for each 10 m travelled along the road, as shown in the diagram.

[diagram not to scale]

Calculate the loss in gravitational potential energy as the cyclist loses 100 m in vertical height and hence calculate the total resistive force on the cyclist and bike.

(gravitational field strength = 10 $N kg^{-1}$)

• A.loss in gravitational potential energy/J: 3200, resistive force/N: $32/\sqrt{101}$
• B.loss in gravitational potential energy/J: 3200, resistive force/N: 3.2
• C.loss in gravitational potential energy/J: 3200, resistive force/N: $32/\sqrt{99}$
• D.loss in gravitational potential energy/J: 100 000, resistive force/N: $1000/\sqrt{101}$
• E.loss in gravitational potential energy/J: 100 000, resistive force/N: 100
• F.loss in gravitational potential energy/J: 100 000, resistive force/N: $1000/\sqrt{99}$

Answer: E

• A.0.40 A
• B.0.60 A
• C.0.80 A
• D.4.0 A
• E.9.0 A

Answer: D

• A.7.2 m
• B.14.4 m
• C.24 m
• D.60 m
• E.120 m

Answer: A

• A.$\frac{F}{mg}$
• B.$\frac{mgv}{F}$
• C.$\frac{mv^2}{2F}$
• D.$\frac{v^2}{2g}$
• E.$vt$
• F.$2vt$

Answer: C

• A.$P = N-4$, $Q = R+1$
• B.$P = N-4$, $Q = R-1$
• C.$P = N-4$, $Q = R-2$
• D.$P = N$, $Q = R-1$
• E.$P = N$, $Q = R-2$
• F.$P = N$, $Q = R-4$

Answer: B

• A.0.20 ms
• B.0.40 ms
• C.0.50 ms
• D.0.80 ms
• E.1.0 ms

Answer: B

The diagrams below show either velocity-time or distance-time graphs for four different objects, P, Q, R and S.

Which graph(s) show an object accelerating at 2.4 $ms^{-2}$?

• A.P only
• B.Q only
• C.R only
• D.S only
• E.P and Q only
• F.Q and R only
• G.P and S only

Answer: B

Consider this graph.

Which one of the following could the graph not represent if all quantities are in SI units?

• A.The variation of the acceleration (y-axis) of a body of mass 5.0 kg with the resultant force acting on the body (x-axis).
• B.The variation of the current (y-axis) through a 5.0 $\Omega$ resistor with the applied voltage (x-axis).
• C.The variation of the kinetic energy (y-axis) of a body of mass 0.4 kg with the square of its speed (x-axis).
• D.The variation of the wavelength (y-axis) of waves with a speed of 0.2 $m s^{-1}$ with their frequency (x-axis).
• E.The variation of the work done (y-axis) by a force of 0.2 N with the distance it moves through in the direction of the force (x-axis).

Answer: D

• A.The process of emission of a gamma ray from a nucleus is called nuclear fission.
• B.The half-life of a radioactive substance is half the time taken for its nuclei to decay.
• C.The number of neutrons in a nucleus is its atomic number (proton number) minus its mass number.
• D.When a nucleus emits a beta particle, there is no change in the number of particles it contains.
• E.When a nucleus emits an alpha particle, one of its neutrons becomes a proton plus an electron.

Answer: D

• A.$\frac{V R_1}{R_1 + R_2}$
• B.$\frac{V^2 R_1}{R_1 + R_2}$
• C.$\frac{V R_1}{(R_1 + R_2)^2}$
• D.$\frac{V^2 R_1}{(R_1 + R_2)^2}$
• E.$\frac{V R_2^2}{(R_1 + R_2)^2}$
• F.$\frac{V^2 R_1^2}{(R_1 + R_2)^2}$

Answer: D

The graph represents the motion of a vehicle during part of a journey.

What is the best estimate of the distance travelled during the part of the journey shown?

• A.100.00 m
• B.107.50 m
• C.115.00 m
• D.6.00 km
• E.6.45 km
• F.6.90 km

Answer: D

A sound wave is produced by a loudspeaker cone, which creates pulses of pressure by moving back and forth between two points X and Y as shown in the diagram.

[diagram not to scale]

The distance between points X and Y is 5.0 mm and the loudspeaker produces pulses of high pressure every 0.20 milliseconds.

The following statements about the sound wave produced are made:

P It has a speed of 25 $m s^{-1}$.

Q It has an amplitude of 5.0 mm.

R It has a wavelength of 5.5 mm.

S It has a frequency of 5.0 kHz.

Which of these statements can be correctly deduced from the information given?

• A.P only
• B.S only
• C.P and Q only
• D.P and R only
• E.Q and S only
• F.R and S only
• G.P, R and S only

Answer: B