085-1263404

### My Journal

All things Mathematical
30 Nov 2018
##### Question 1

A bullet of mass is fired with speed into a fixed block of wood and is brought to rest in a distance . Find the resistance to motion assuming it to be constant.

Another bullet also of mass is then fired with speed into another fixed block of thickness , which offers the same resistance as the first block. Find the speed with which the bullet emerges, and the time it takes to pass through the block.

##### Question 2

Prove that the formula represents the distance travelled in time by a body moving in a straight line with constant acceleration .

A train takes minutes to travel between two stations and which are meters apart. It starts from rest at and finishes at rest at , by travelling with uniform acceleration for the first minute and with uniform deceleration for the last minute. Find the train’s constant speed during the remainder of the journey.

If a second train, travelling with a constant speed of m/min, in the same direction passes as the first train leaves this station, find when overtaking occurs. (The lengths of the trains may be neglected).

##### Question 3

A particle is projected under gravity with an initial velocity at an angle to the horizontal. Find its position and the direction of motion after time in terms of in terms of , , and .

A particle is projected from the top of a cliff which is ft. above sea level and the angle of projection is to the horizontal. If the greatest height reached above the point of projection is ft, find the speed of projection and the time taken to reach this greatest height.

Find when and where the particles strikes the sea.

(Take to be ft/sec ).

##### Question 4

Prove that the bob of a simple pendulum moves in simple harmonic motion – stating any assumptions made.

The string of such a pendulum is ft. long and the bob is released from rest when at a distance ft from the equilibrium position. Calculate the time taken to travel halfway to the equilibrium position and the speed of the bob then.

(Take to be ft/sec ).

##### Question 5

By deriving an expression for the necessary acceleration, prove that a particle of mass moving in a circle of radius with speed must have a force of magnitude pointing towards the centre acting on it.

A particle of mass lbs. moving on the inside smooth surface of a fixed spherical bowl of radius ft is describing a horizontal circle of radius ft. Find the constant speed of rotation and the reaction of the sphere on the particle.

(Take to be ft/sec ).

##### Question 6

Show that the centre of gravity of a uniform triangular lamina coincides with the centre of gravity of three equal particles placed at the vertices of the triangle. Hence find the centre of gravity of a uniform trapezium , of weight , in which and .

A particle of weight is attached at and the system is suspended by a string attached to the midpoint of . If in the position of equilibrium is vertically above show that .

##### Question 7

A particle of mass lbs. is placed on a rough inclined plane. The least force acting up the plane which will prevent the particle slipping down the plane is lbs. weight. The least force acting up the plane which will make the particle slip upwards is lbs wt. Show that the coefficient of friction is and that the inclination of the plane is where .

Find the least force required to move the particle up the plane.

##### Question 8

Two equal uniform rods and each of weight are freely jointed at . The system is suspended freely from and a horizontal force is applied at the lowest point . If in the equilibrium position the inclination of to the downward vertical is , find the corresponding inclination of and the supporting force at .

##### Question 9

A small uniform cylinder of density , mass , total length and uniform cross section floats in a liquid of density with its axis vertical. Find the thrust on the cylinder when it is displaced vertically in the liquid, without being completely immersed, through a distance from the equilibrium position. Show that if it is released in this position, it will oscillate with simple harmonic motion of period .

##### Citation:

State Examinations Commission (2018). State Examination Commission. Accessed at: https://www.examinations.ie/?l=en&mc=au&sc=ru

Malone, D and Murray, H. (2016). Archive of Maths State Exams Papers. Accessed at: http://archive.maths.nuim.ie/staff/dmalone/StateExamPapers/

##### Licence:

“Contains Irish Public Sector Information licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence”.

The EU Directive 2003/98/EC on the re-use of public sector information, its amendment EU Directive 2013/37/EC, its transposed Irish Statutory Instruments S.I. No. 279/2005, S.I No. 103/2008, and S.I. No. 525/2015, and related Circulars issued by the Department of Finance (Circular 32/05), and Department of Public Expenditure and Reform (Circular 16/15 and Circular 12/16).

Note. Circular 12/2016: Licence for Re-Use of Public Sector Information adopts CC-BY as the standard PSI licence, and notes that the open standard licence identified in this Circular supersedes PSI General Licence No: 2005/08/01.