**UNIVERSITY EXAMINATIONS: 2012/2013**

**FIRST YEAR EXAMINATION FOR THE BACHELOR OF SCIENCE **

**IN INFORMATION TECHNOLOGY**

**BIT 1102 FOUNDATION PHYSICS FOR IT**

**DATE: DECEMBER, 2012 TIME: 2 HOURS**

**INSTRUCTIONS: Answer Question ONE and any other TWO**

**QUESTION ONE**

a) (i) State the three basic quantities of matter. (3 Marks)

(ii) Define a force and give two examples. (3 Marks)

(iii) State Newton’s Laws of Motion. (3 Marks)

b) A hawk is hovering above a field at a height of 50 m. It sees a mouse directly below

it and dives vertically with an acceleration of 9 m/s2

(i) At what speed will it be traveling just before the ground.

(ii) How long does it take to reach the ground (4 Marks)

c) (i) Define a wave (2 Marks)

ii) What is Doppler effect? (2 Marks)

iii) A train has a whistle, which emits a 400 Hz sound. You are stationary and you

hear the whistle, but the pitch is 440 Hz. How fast is train moving towards or

away from you? (4 Marks)

d) i) State the Work-Energy theorem (2 Marks)

ii ) When a body is moved from sea level to mount Kenya, what changes: the body’s,

it’s weight or both? Explain your answer. (3 Marks)

e) State two differences between real and virtual images. (4 Marks)

**QUESTION TWO**

a) A car is traveling at the town speed limit of 13 m/s when the driver sees a child run out

into the road in front of the car and fall down. The driver has a reaction time of 0.4 s

and the brakes can slow the car at a constant rate of 2.6 m/s2

. The car stopped just a

few centimeters from the child. How far in front of the car was the child when the

driver saw him. (8 Marks)

b) Explain how standing wave is produced (4 Marks)

c) The light beam below is incident on surface 1 at an angle

and on surface 2 of

the prism at the critical angle. Determine the incidence angle

. (8 Marks)

**QUESTION THREE**

a) A bullet of mass 4 g leaves the barrel of a rifle at a speed of 300 m/s. The barrel is 0.74

m long.

i) What is the average force exerted on the rifle? (4 Marks)

ii ) The rifle has a mass of 1.5 kg and the inexperienced user holds it loosely, so that it

is 0.02 m away from his shoulder, when it is fired. Estimate the speed at which the

rifle butt hits the user’s shoulder. (6 Marks)

b) The commercial unit of electricity is the kilowatt-hour(kWh), defined as the electrical

energy consumed when a 1kW appliance is turned on for 1 hour.

i) Calculate the amount of energy (in Joules) in 1 unit of electricity (2 Marks)

ii) Estimate the electricity cost for operating a power tool rated at 6000 W running for

one month of 20 working days (8:00 am to 4:00 pm) if 1 unit costs 7.5 Ksh.

(5 Marks)

iii) State three techniques of polarizing light. (3 Marks)

42o

Surface 1

Surface 2

600

air

**QUESTION FOUR**

a) i) Define a magnetic field? (2 Marks)

ii) Write down an expression for the force experienced by the conductor due to the

magnetic field. (2 Marks)

iii) What is the magnetic field due to a solenoid length 15.0cm of 120 turns carrying a

current of 3A. (3 Marks)

b) i) State Faraday’s of electromagnetic induction (2 Marks)

ii) A proton moves in a circle of radius 20 cm perpendicular to a magnetic field

B = 0.05 T. Find the momentum of the proton. (4 Marks)

c) i) State the three states of matter. (3 Marks)

ii) The mass of moon is 7.35 ×10 22 kg and its mean radius is 1.74 ×106

. Taking the

moon as a perfect sphere, compute its average density in kg/ m3

. Express this in

g/ m3

. (4 Marks)

**QUESTION FIVE**

a) An echo sounder in a ship produces a sound pulse and an echo is received from the

sea bed after 0.4 s. Assuming the speed of sound in water is 1500 m/s, calculate the

depth of the sea bed. (4 Marks)

b) A football is kicked vertically upward on the moon with an initial speed of 35 m/ s. If

the acceleration due to gravity is 1.6 m/s-2

on the moon, determine

i ) the maximum height attained by the ball.

ii ) the time to taken to reach maximum height.

iii ) the velocity 30.0 s after it is kicked.

iv ) the time when the ball’s height is 100 m (10 Marks)

c) i) Suppose the superhero had flown 150 m at an angle 120o with respect to the positive

x-axis. Find the components of the displacement vector. (3 Marks)

ii ) Suppose instead the superhero had leaped with a displacement having x-

component of 32.5 m and y- component of 24.3 m. Find the magnitude and

direction of the displacement vector. (3 Marks)