STAGE 2 PHYSICSSkills Assessment Task:

PROJECTILE MOTION and UNIFORM CIRCULAR MOTION

Purpose

This assessment provides you with the opportunity to demonstrate your ability to represent, analyse, and interpret investigations in physics through the use of technology and numeracy skills, communicate knowledge and understanding of the concepts and information of physics using the appropriate literacy skills of physics and demonstrate and apply knowledge and understanding of physics to a range of applications and problems relating to electricity and magnetism.

Description of assessment

In this assessment you need to: communicate your knowledge and understanding clearly and concisely use physics terms correctly present information in an organised and logical sequence include only information that is relevant to the question use clearly labelled diagrams that are related to your answer show all steps and reasoning in your answer give answers with appropriate units and direction.You may use the formula sheet provided to select appropriate formulae.

Assessment conditions

This is a supervised 70 minute closed-book assessment completed under test conditions in one double lesson. A calculator may be used.

YEAR 12 PHYSICS: SUMMATIVE TEST ONE: Name:

PROJECTILE MOTION AND UNIFORM CIRCULAR MOTION

QUESTION 1

The hammer throw is an olympic event.

The athlete throws a heavy metal ball attached by a wire to a handle.

(a) The hammer thrower swings the hammer round in a circle with a constant radius (0.75 m) before letting go.

He swings the hammer slowly at first and then faster.

(i) Identify the force causing the centripetal acceleration in the above example (1 mark) A2

(ii) State the change to the magnitude of this force as the speed increases.

(1 mark) A2

(b) Determine the period of rotation if the hammer is swung 10 complete times over a period of 6.00 seconds

(1 mark) AE1

(c) Show that the magnitude of the centripetal acceleration is equal to 82 ms -2

(4 marks) A2

(d) The magnitude of the force causing the centripetal acceleration in this example is 600 N.

(i) Determine the mass of the hammer given the magnitude of the centripetal acceleration in (c) above.

(2 marks) A2

(ii) Identify the letter corresponding to the direction of the centripetal force on the diagram below:

(1 mark) A2

(iii) State the magnitude of the centripetal force if the radius is halved

(1 mark) A2

QUESTION 2

The diagram shows the apparatus used by two students to determine the changes in the magnitude of the speed as the radius of the circular path was increased.

(a) Complete the table below by determining the values of v2

Radius (m) speed (m.s-1) speed squared (m2.s-2)

0.300 2.05

0.350 2.11

0.400 2.37

0.450 2.62

0.500 2.65

0.550 2.77

0.600 3.05

(2 marks) I4

(b) State the independent variable in this experiment

(1 marks) I4

Rubber stopperRubber stopper (0.130 kg)

Weight (0.200 kg)

(c) Plot the data on the space provided below ensuring that you label the axis, state the units and use an appropriate scale.

(5 marks) I4

(d) State the feature of your graph that shows that the data obtained is of low precision

(1 mark) AE1

(e) Identify the type of error which lowers the precision of the experimental data

(1 mark) AE1

(f) Use the graph to determine the speed of the rubber stopper at a radius of 0.420 m

You must show a ruled interpolation on the graph to obtain the value

(3 marks) AE1

(g) Calculate the slope of the line of best fit. (Remember to include units).

(3 marks) AE1

(h) Determine the equation of this line, i.e. find the relationship connecting v2 and r.

(1 mark) AE1

(i) Explain why Mg=mv2

r given the diagram opposite:

(2 marks) AE1

(j) Use the slope to determine the value of g in the experiment

(2 marks) AE1

(k) Comment on the accuracy of the experimentally determined value of g given the true value of 9.81 ms-2

(1 mark) AE1

(l) Identify the type of error which effects the accuracy of the experimental data

(1 mark) AE1

(0.130 kg)

(0.200 kg)

QUESTION 3

Construction began on building the famous Daytona Speedway in 1957. The radius of the track is 150 m.

To build high banking curves (310), crews had to use millions of tons of soil from the tracks infield.

(a) On the diagram below, draw and label the forces acting on the car, of mass m, as it travels around a banked curve of radius r without relying on friction.

You must use a ruler for your vector diagram

(4 marks) KU3

(b) Derive the expression tanθ= v2

rg given the forces acting on the car.

(3 marks) KU1

(c) Determine the maximum speed at which a car can travel around the banked curve (310) without relying on friction.

(3 marks) A2

QUESTION 4

A tennis player serves a ball from a height of 2.51 m at 18.0 ms-1 in a horizontal direction. The ball just clears the net which is 1.00 m high.

In this question, assume air resistance is negligible and that g = 9.81 ms -2

(a) Show that the ball takes approximately 0.555 seconds to reach the net after being served

(3 marks) A2

(b) Determine the vertical component of velocity as it passes over the net

(2 marks) A2

(c) Calculate the magnitude and direction of the resultant velocity of the ball as it passes over the net.

Draw a fully labelled vector diagram (with a ruler) in the space provided.

(6 marks) A2

QUESTION 5

The shot put is an Olympic event which involves the throwing of a large heavy sphere (the shot) as far as possible.

(a) In one event, a shot put thrower launched the shot with an initial velocity of 10.5 ms -1 at an angle of 440 above the horizontal. The shot had a time of flight of 3.02 seconds

(i) Calculate the horizontal component of velocity of the shot

(2 marks) A2

(ii) Determine the maximum horizontal range of the shot

(2 marks) A2

(b) Explain why a greater horizontal range is achieved by a shot put thrower who launches the shot from a greater height above the ground.

(2 marks) KU1

QUESTION 6

EXTENDED RESPONSE

Two balls are launched with the same initial velocity, at an angle of θ above the horizontal. Air resistance is a force which opposed the motion of the balls as they move through the air. If different forces of air resistance act on the balls, the motion of the balls will be different.

Write an extended response discussing the following:

Identify and explain three factors that affect the magnitude of the force of air resistance opposing the motion of each projectile.

Explain the effect that air resistance has on the maximum height and maximum horizontal range achievable by the balls.

Credit will be given for answers which are clear and expressed in a concise and coherent manner

(14 marks) KU3