Introductory Physics - Antimatter



WIT

HIGHER CERTIFICATE IN SCIENCE

HIGHER CERTIFICATE IN AGRICULTURAL SCIENCE

BSc IN FOOR SCIENCE WITH BUSINESS

SEMESTER ONE

EXAMINATION:

INTRODUCTORY PHYSICS

YEAR 1

December 2008 DURATION: 2 HOURS

EXAMINERS: Ms CATHERINE WALSH

Dr CORMAC O’RAIFEARTAIGH

Mr JAMES KELLY

INSTRUCTIONS TO CANDIDATES

1 ANSWER FOUR QUESTIONS

2. ALL QUESTIONS CARRY EQUAL MARKS

3. PHYSICAL CONSTANTS ON BACKPAGE

WATERFORD INSTITUTE OF TECHNOLOGY

Section A

Question One

(a) (i) Define and state the S.I. unit of measurement for the following quantities

speed, velocity

(ii) Explain the difference between a vector and a scalar quantity giving an example of each.

(iii) Convert each of the following to correct S.I. units and use scientific notation.

23 g, 2 hours, 100 km hr-1, 1263 mm2,

(9 marks)

(b) (i) Define and state the S.I. unit of measurement for the following quantities

acceleration, Force

ii) State Newton’s First and Second laws.

iii) A car starts from rest and moves with uniform acceleration over a distance of 130m in a time of 10 s. Calculate the final velocity and the acceleration of the car.

iv) If the car then stops accelerating and continued to travel at constant velocity how far will it travel in 8 mins.

v) If the driver then spots a car breaking in front and slams on the breaks which causes the car to decelerate at a rate of –5.4 ms-2. Calculate how long it will take the car to come to a complete stop and how far the car will have travelled in this time

(16 marks)

(Total 25 marks)

Question Two

(a) (i) Define the term linear momentum and state its S.I. unit of measurement.

(ii) State the Principle of Conservation of Linear Momentum.

(iii) Explain the difference between elastic and inelastic collisions.

(iv) An object of mass 726 g moving with a steady velocity of 10.55 ms-1 along the + x axis collides with a stationary second object of triple its mass. If the two masses couple together calculate their common velocity after the collision.

(v) Calculate the total kinetic energy of the masses from part (iv) before and after the collision. Based on this answer was the collision elastic or inelastic.

(14 marks)

(b) A ball of mass 1.5 kg is dropped from a window that is 50 m above the ground.

(i) How long does it take the ball to fall ?

(ii) Calculate the kinetic energy of the ball as it hits the ground.

(4 marks)

(c ) Describe in detail an experiment to determine the coefficient of friction between two surfaces.

(7 marks)

(Total 25 marks)

Question Three

(a) (i) Define the terms energy, power and efficiency stating the S.I. units of measurement of each.

ii) State the Law of Conservation of Energy.

(iii) An engine can raise 240 kg of coal every minute out of a mine shaft 160m deep. If it is 70% efficient calculate both the work done by the engine in 1 hour and its power rating.

(11 marks)

(b) Explain how an object moving at constant speed can have a force acting on it.

(2 marks)

(c) A cd accelerates uniformly from rest to its operational speed of 500 rpm in 3.7 s. The cd plays for 48 minutes and then comes uniformly to a stop in 4.25 s.

i) Convert the operational speed into correct S.I. units.

ii) Calculate a value for the angular acceleration of the cd while it is accelerating.

iii) If the diameter of the cd is 120mm calculate its linear velocity at the edge of the cd at it operational speed.

iv) Calculate the linear velocity, at a point in the cd half way between the edge and the center, again at its operational speed.

v) Calculate the number of rotations that the cd makes while it is in operation.

vi) Calculate a value for the angular deceleration while the cd is coming to a stop.

vii) Calculate the number of revolutions that the cd makes while it is coming to a stop.

(12 marks)

Question 4

(a)(i) State Newton’s Third Law of Motion.

(ii) Define the terms Frictional Force and the coefficient of friction and state its S.I. units.

(5 marks)

b) (i)Draw a vector diagram to represent all the forces acting on a block of mass m (kg) placed on a plane inclined at an angle θ to the +x axis , if the coefficient of friction between the block and the plane surface is μ. For each force derive the equation for the magnitude of the force and indicate its direction.

(ii) Derive the equation for the total force acting on the mass down the incline.

(8 marks)

c) How long will it take a mass of 1655 g to slide from rest a distance of

88 cm down a plane inclined at an angle of 45o to the horizontal if

i) the plane is frictionless

ii) the coefficient of friction is 0.27.

(12 marks)

Section B

Answer at least one Question from this section

Question 5.

(a) (i) Define the terms Density and Pressure stating its SI unit of measurement of each.

(ii) Derive the expression

P = ρ g h

for the pressure due to a height, h , of liquid of density ρ.

(iii) Atmospheric pressure on a particular day is 755mm(Hg). Calculate the absolute pressure at a depth of 15m in sea-water on that same day.

(11 marks)

(b)(i) State Archimedes Principle.

(ii) A metal object weighs 6 N in air, 5.2 N in water. Calculate the mass, the relative density and density of the metal.

(7 marks )

(c)(i) Define Youngs’ Modulus

(ii) A copper wire of length 1.3 m and diameter 0.32 mm is extended when a load of 7.921 kg is applied. Calculate the extension produced and the work done.

(7 marks)

Question 6

(a) Define the following terms as applied to a wave motion for each quantity include a diagram:

wavelength, frequency and periodic time.

(8 marks)

(b) A source emits a sound of frequency 5000 Hz in air. Calculate its wavelength.

(2 marks)

I Explain the difference between a transverse and a longitudinal wave, giving one example of each.

(4 marks)

d) Define the terms intensity and intensity level of sound stating the S.I. unit of measurement of each.

(4 marks)

e) A small source emits sound uniformly in all directions. If the intensity of the sound is 4 μW m-2 at a point X which is at a distance of 3 m from the source.

(i) Calculate the intensity level of the source.

(ii) Calculate the intensity level at a point Y a distance of 10 m from the source.

(7 marks)

PHYSICAL CONSTANTS

g ( acceleration due to gravity) = 9.81 ms-2

velocity of sound in air = 340 m s-1

Density of water = 1000 kg m-3

Density of sea-water = 1003 kg m-3

Density of mercury = 13600 kg m-3

Ιο ( threshold intensity of sound ) = 1 x 10 -12 W m -2

Y(Youngs’ Modulus of copper) = 110 GN m-2

Some Useful Equations

Linear Motion with constant acceleration

v = u + a t s = u t + ½ a t2 v2 = u2 + 2 a s

Potential Energy. = m g h

Kinetic Energy. = ½ m v2

Centripetal acceleration = [pic] = [pic]

There are other values and equations on page 40 of the Mathematics (Log) Tables that you may also find useful.

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