Mechanics | Relativity Answers

(a) Define the following terms: (i) Vibration (ii) Momentum (iii) Coefficient of restitution
(b) What is power? Hence, determine the power input for a motor necessary to lift 300 N at a constant rate of 5 m/s. The efficiency of the motor is ∈= 0.65.
(ii) Starting from rest, the motor boat travels around the circular path,

(i) State the Newton’s second law of motion.
(ii) State the Newton’s law of gravitation.
(b) (i) The 80 kg block in the diagram below rests on a horizontal plane. Find the magnitude of the
force P required to give the block an acceleration of 2.5 m/s^2
to the right. The coefficient of
kinetic friction between the plane

a) (i) State Kepler’s second and third laws of planetary motion.
(ii) With the aid of suitable diagrams, differentiate between central impact and oblique impact.
(b) (i) A 12kg block is supported by the spring shown below. If the block is moved vertically
downward from its equilibrium position and released, determine (a) the period and frequency of
the resultant motion, (b) the maximum velocity and acceleration of the block if the amplitude of
its motion is 40mm.
(ii) If

(a) (i) Explain the term “Coefficient of restitution”.
(ii) Differentiate between free vibration and forced vibration.
(b) (i) Starting from rest, a motor boat travels around the circular path,

1. The motion of a particle is defined by the relation

A steady, incompressible, two-dimensional velocity field is given by
the following components in the xy-plane:

A 50-cm × 30-cm × 20-cm block weighing 150 N is to be moved at a
constant velocity of 0.80 m/s on an inclined surface with a friction
coefficient of 0.27. (a) Determine the force F that needs to be applied
in the horizontal direction. (b) If a 0.40-mm-thick oil film with a
dynamic viscosity of 0.012 Pa∙s is applied between the block and
inclined surface, determine the percent reduction in the required
force.

A long solid cylinder of radius 0.8 m hinged
at point A is used as an automatic gate, as
shown in Fig. beside. When the water level
reaches 5 m, the gate opens by turning about
the hinge at point A. Determine (a) the
hydrostatic force acting on the cylinder and
its line of action when the gate opens and (b)
the weight of the cylinder per m length of the
cylinder.

Balloons are often filled with helium gas
because it weighs only about one-seventh of
what air weighs under identical conditions.
The buoyancy force, which can be expressed
as

a) Define the following terms: (i) Displacement (ii) Velocity (iii) Acceleration (iv) Distance (v)
Speed.
(b) A particle is constrained to travel along the path