DP Physics Questionbank

Water flows through a constricted pipe. Vertical tubes A and B, open to the air, are located along the pipe.

Describe why tube B has a lower water level than tube A.

Explain, with reference to energy in the system, the amplitude of oscillation between

(i) t = 0 and t_A.

(ii) t_A and t_B.

Calculate the Q factor for the system.

Estimate the magnitude of the force on the ball, ignoring gravity.

Explain the origin of the buoyancy force on the air bubble.

The Q factor of the system increases. State and explain the change to the graph.

With reference to the ratio of weight to buoyancy force, show that the weight of the air bubble can be neglected in this situation.

On the diagram, draw an arrow to indicate the direction of this force.

State and explain the displacement of the sine wave vibrator at t = 8.0 s.

The vibrator is switched off and the spring continues to oscillate. The Q factor is 25.

Calculate the ratio $\frac{\text{energy stored}}{\text{power loss}}$ for the oscillations of the spring–mass system.

State what is meant by damping.

On the graph, sketch a curve to show the variation with driving frequency of the amplitude when the damping of the system increases.

Calculate the terminal speed.

State one assumption you made in your estimate in (a)(i).

Determine the force exerted by the spring on the sphere when the sphere is at rest.

Outline the effect on $\mathrm{Q}$ of changing the oil to one with greater viscosity.

Determine the terminal velocity of the sphere.

The sphere oscillates vertically within the oil at the natural frequency of the sphere-spring system. The energy is reduced in each cycle by $10 \%$. Calculate the $\mathrm{Q}$ factor for this system.

A solid cube of side 0.15 m has an average density of 210 kg m^–3.

(i) Calculate the weight of the cube.

(ii) The cube is placed in gasoline of density 720 kg m^–3. Calculate the proportion of the volume of the cube that is above the surface of the gasoline.

The room temperature slightly increases from 25 °C, causing the buoyancy force to decrease. For this change in temperature, the ethanol density decreases from 785.20 kg m^–3 to 785.16 kg m^–3. The average viscosity of ethanol over the temperature range covered by the thermometer is 0.0011 Pa s. Estimate the steady velocity at which the 25 °C sphere falls.

Outline why the light detected from Jupiter and Vega have a similar brightness, according to an observer on Earth.

Show that the distance to Vega from Earth is about 25 ly.

Using the graph, determine the buoyancy force acting on a sphere when the ethanol is at a temperature of 25 °C.

Explain why it would be uncomfortable for the farmer to drive the vehicle at a speed of 5.6 m s^–1.

When the ethanol is at a temperature of 25 °C, the 25 °C sphere is just at equilibrium. This sphere contains water of density 1080 kg m^–3. Calculate the percentage of the sphere volume filled by water.

Outline whether it is reasonable to assume that flow is laminar in this situation.

State the difference in terms of the velocity of the water between laminar and turbulent flow.

The water level is a height H above the turbine. Assume that the flow is laminar in the outlet pipe.

Show, using the Bernouilli equation, that the speed of the water as it enters the turbine is given by v = $\sqrt{2gH}$.

Calculate the Reynolds number for the water flow.

Describe the motion of the spring-mass system.

calculate the Q at the start of the motion.

Outline whether your answer to (a) is valid.

Show that the velocity of the fluid at X is about 2 ms^–1, assuming that the flow is laminar.

Estimate the Reynolds number for the fluid in your answer to (a).

Draw a graph to show the variation of amplitude of oscillation of the system with frequency.

The Q factor for the system is reduced significantly. Describe how the graph you drew in (a) changes.

State and explain the direction of motion of the mass at this instant.

The density of water is 1000 kg m^–3. Calculate u.

The oscillator is switched off. The system has a Q factor of 22. The initial amplitude is 10 cm. Determine the amplitude after one complete period of oscillation.

The weight of the sphere is 6.16 mN and the radius is 5.00 × 10^-3 m. For a fluid of density 8.50 × 10² kg m^-3, the terminal speed is found to be 0.280 m s^-1. Calculate the viscosity of the fluid.

Show that, when the speed of the train is 10 m s-1, the frequency of the periodic force is 0.4 Hz.

Draw and label the forces acting on the sphere at the instant when it is released.

State one condition that must be satisfied for the Bernoulli equation

$\frac{1}{2}$ ρv² + ρgz + ρ = constant

to apply

Calculate the difference in pressure between X and Y.

Another system has the same initial total energy and period as that in (a) but its Q factor is greater than 25. Without any calculations, draw on the graph, the variation with time of the total energy of this system.

The Q factor for the system is 25. Determine the period of oscillation for this system.

The point of suspension now vibrates horizontally with small amplitude and frequency 0.80 Hz, which is the natural frequency of the pendulum. The amount of damping is unchanged.

When the pendulum oscillates with a constant amplitude the energy stored in the system is 20 mJ. Calculate the average power, in W, delivered to the pendulum by the driving force.

After one complete oscillation, the height of the pendulum bob above the rest position has decreased to 28 mm. Calculate the Q factor.

Explain why the levels of the liquid are at different heights.

The density of the liquid in the tube is 8.7 × 10²kg m^–3 and the density of air is 1.2 kg m^–3. The difference in the level of the liquid is 6.0 cm. Determine the speed of air at A.