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### My Journal

All things Mathematical
21 Nov 2018
##### Question 1 is a triangle in which , , . Forces of , , lb. wt. act along , , , respectively. How far from does the line of action of their resultant cut ?.

Find the magnitude of the resultant in lb. wt., correct to one place of decimals, and find the angle which its line of action make with , correct to the nearest degree.

##### Question 2

Explain the terms “limiting friction,” “coefficient of friction.”

When a truck is ascending an incline of in with a uniform acceleration of ft. per sec. per sec., a box on the floor of the truck is just about to slide backwards. Show by diagram the forces acting on the box, and find the coefficient of friction between the box and the floor of the truck.

##### Question 3

A man is cycling at m.p.h. in a steady wind. When he cycles in a direction north of east the wind appears to him to blow directly from the east. When he cycles due east the wind appears to him to blow from the south-east. Find the velocity of the wind in magnitude and direction.

##### Question 4

Two bodies, of mass gm. and gm. respectively, are lying on a smooth horizontal bench which is feet high. The gm. body is at the edge of the bench and the gm. body is feet away in a direction perpendicular to the edge, the bodies being connected by a light inextensible string feet long. If the gm. body is pushed gently over the edge, find how many seconds later it will reach the ground.

##### Question 5

Derive an expression for the total time of flight of a projectile in terms of its initial velocity and angle of projection. , , , are three collinear points on a horizontal plane. A projectile fired from passes over at a height of feet and reaches its greatest height as it passes over . If feet and the total time of flight of the projectile is seconds, find its initial velocity.

##### Question 6

A mass of lb. suspended from a fixed point by a light inextensible string feet long acts as a conical pendulum, the mass describing a horizontal circle at a uniform rate of revolutions per minute. Find the tension in the string, in lb., wt., and the inclination of the string to the vertical.

##### Question 7

A particle is moving along a straight line so that is distance (cms.) from a fixed point at the time (secs.) is given by the formula .

Show that the motion is simple harmonic and find the periodic time and the maximum velocity.

If the velocity of the particle at is cm. per sec., find its acceleration at , and find the least time the particle takes to travel to from .

[See Tables, p. 30].

##### Question 8

A triangular lamina is immersed in a liquid of specific gravity so that the vertex is at the surface and the sides is vertical. If , , , find the thrust of the liquid on in ounces. is a point on such that the thrust of the liquid on is give-ninths of the thrust on . Find the length of .

[A cubic foot of water weights lb.]

##### Question 9 is a quadrilateral lamina in which , , , . Find the perpendicular distance of the centre of gravity of from .

Find, also, the perpendicular distance of the centre of gravity of from .

##### 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/

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