Cork Institute of Technology
Bachelor of Engineering (Honours) in Structural Engineering – Stage 1
Bachelor of Engineering in Structural Engineering – Stage 1
(NFQ – Level 8)
Autumn 2005
PHYSICS
(Time: 3 Hours)
Answer FIVE questions only.
Show ALL working to gain full marks.
Assume: g = 10.0 ms-2
Examiners: Mr. T. Corcoran
Prof. P. O’Donoghue
Dr. M. E. Woods
Q1. (a) (i) Sketch a fully-labelled ray diagram of a refracting astronomical telescope
operating in normal adjustment incorporating two converging lenses of focal
length fo and fe [fo > fe]. Indicate all relevant distances, angles and images.
(ii) State the location, magnification, orientation and nature of the final image.
(iii) What additional device is incorporated into a terrestrial telescope? How
does this device affect the final image? [12 marks]
(b) A man outside a swimming pool looks at a coin which he has dropped into the pool which
is 3.0 m deep. A ray from the coin to the man has an angle of incidence of 20o in the water
at the water/air interface. The refractive index of water is 1.33 and the refractive index of
air is 1.00.
(i) State Snell’s Law and hence calculate the angle of refraction in the air.
(ii) Determine the apparent depth of the coin in the pool. [8 marks]
Q2. (a) State Newton’s Third Law. [2 marks]
(b) A block of mass 6.0 kg on a smooth, flat, horizontal table top, is connected by a taut
string over a frictionless pulley at the edge of the table, to another block of mass 9.0 kg,
which hangs vertically freely. Determine:
(i) The acceleration [a] of the blocks.
(ii) The tension [T] in the string. [8 marks]
(c) A car of mass 1200 kg travels with a steady velocity of 25 ms-1 along a horizontal road.
The frictional force is 6.0 kN. Calculate:
(i) The coefficient of dynamic friction between the car and road.
(ii) The power of the engine. [10 marks]
