SECTION B
QUESTION 2 (15)
2.1 A vehicle moving with a velocity v experiences a force F, due to air
resistance, given by;
F
=
1
-ceavf3
AY
2
Where is Q the density of air, A is the cross-sectional area of the vehicle and C
is the dimensionless quantity called the drag coefficient.
2.1 .1 Use dimensional analysis to find a, and y
(7)
2.2 When a solid sphere moves through a liquid, the liquid opposes the motion with
a force F. The magnitude of F depends on the coefficient of viscosity 11of the
liquid, the radius r of the sphere and the speed of the sphere. Use dimensional
analysis to derive a formula for the force (F).
(8)
QUESTION 3 (16)
3.4 Consider the following vectors:
A = T+ 3 J- 2 k and B =5 T- 3 k
(i) Find: Ax B
(5)
(ii) Determine a unit vector that is perpendicular to both vectors, A and B (3)
i - J k. 3.5 The position f of an object is given by 1.0 t3 2.0 t2 + 3.0 t2 m (with t in
seconds). Determine;
(i) he magnitude of the position f when t = 3 seconds
(4)
(ii) the acceleration of the particle for 3 seconds.
(4)
QUESTION 4 (15)
4.1 State the law of conservation of momentum.
(3)
4.2 A weight of mass mis at rest at O when suspended from a spring, as shown
in figure 1. 0. The energy applied (E) of pulling down the spring is
combination of potential energy (PE) and kinetic energy (KE). When released,
the spring oscillates between positions A and B.
4