### My Journal

Maths Grinds
9 Apr 2018
##### Question 1

A ship $A$ sailing due N. at 15 miles per hour is at a certain instant 41 miles due E. of another ship B which is sailing E. at 12 miles per hour. When will the ships be nearest together?

##### Question 2

Explain the variations of the forces between the floor of a lift and the feet of a man standing on it during the upward and downward journeys from rest to rest.

##### Question 3

A bullet weighing $1$ oz. is fired horizontally into a block of wood weighing 12 lbs. suspended so that the wood and the bullet embedded in it swing without rotation to a height of 2 ft. 6 in. Find the velocity of the bullet on entering the wood.

##### Question 4

What is meant by Simple Harmonic Motion?

Show that the bob of a simple pendulum moves with Simple Harmonic Motion when the angle of swing is small.

Find an expression for the periodic time of the pendulum.

##### Question 5

Show that the area under a force distance diagram represents work done.

The force exerted by a spring is proportional to the extension of the spring and a forces of 5 lbs. wt. produces an extension of 2 ins. Show graphically the relation between the tension and the extension and deuce the work done in extending the spring through 10 inches.

Show that the work done on such a spring when stretched $a$ feet is $\frac{Pa}{2}$ ft. lbs., where $P$ lbs. wt. is the tension for extension $a$ feet.

##### Question 6

A body of $W$ lbs. can just be maintained at rest on a rough inclined plane by a force $P$ lbs. wt. acting along the plane, of by a force $Q$ lbs. wt. acting horizontally.

Show that $\frac{\sec^2 \varphi}{P^2} = \frac{1}{Q^2} + \frac{1}{W^2}$ where $\varphi$ is the angle of friction.

##### Question 7

Find the acceleration of a particle which moves with uniform speed in a circle.

A trin is to travel round a curve of radius $r$ ft. If $a$ ft. is the distance between the rail, find the height $b$ ft. to which one rail should be raised above the level of the other  so as to eliminate side pressure on the rails for trains travelling at $v$ ft. per sec.

If a train of $W$ tons weight moves on such a track with speed $nv$ feet per sec. prove that there is now a side pressure on rails of approximately $W \frac{b}{a} \left(n^2-1\right)$ tons wt.

##### Question 8

A shot at the instant of projection breaks into two parts of masses $m_1$ and $m_2$ lbs., the first part starting with velocity $v_1$ at an angle $\theta_1$ to the horizontal and the second with velocity $v_2$ at an angle $\theta_2$ to the horizontal. Show that the centre of gravity moves at if the whole shot started with velocity $v$ at an angle $\theta$ to the horizontal; the find $v$ and $\theta$ in terms of $m_1$, $m_2$, $v_1$, $v_2$, $\theta_1$, $\theta_2$.

##### Citation:

State Examinations Commission (2023). State Examination Commission. Accessed at: https://www.examinations.ie/?l=en&mc=au&sc=ru

Malone, D and Murray, H. (2023). Archive of Maths State Exams Papers. Accessed at: http://archive.maths.nuim.ie/staff/dmalone/StateExamPapers/

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