Question
(a)Mass, length and time are SІ base quantities.
State two other base quantities.
1. …………………………………………………………………………………………………………………………….
2. …………………………………………………………………………………………………………………………….
(b) A mass m is placed on the end of a spring that is hanging vertically, as shown in Fig. 1.1.
The mass is made to oscillate vertically. The time period of the oscillations of the mass is T.
The period T is given by
\(T = C\sqrt{\frac{m}{k}}\)
where C is a constant and k is the spring constant.
Show that C has no units.
Answer/Explanation
(a)
temperature
current
(allow amount of substance and luminous intensity)
(b)
base units of force constant: kgms–2 m–1 or kg s–2
base units of time and mass: s and kg
base units of C: s (kgs–2 / kg)1/2 cancelling to show no units
Question
(a) Distinguish between mass and weight.
mass: ……………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………
weight: ………………………………………………………………………………………………………………
…………………………………………………………………………………………………………………………[2]
(b) An object O of mass 4.9 kg is suspended by a rope A that is fixed at point P. The object is pulled to one side and held in equilibrium by a second rope B, as shown in Fig. 2.1.
Rope A is at an angle θ to the horizontal and rope B is horizontal. The tension in rope A is 69 N and the tension in rope B is T.
(i) On Fig. 2.1, draw arrows to represent the directions of all the forces acting on object O. [2]
(ii) Calculate
1. the angle θ,
θ = …………………………………………° [3]
2. the tension T.
T = ………………………………………. N [2]
Answer/Explanation
Ans:
(a) mass is the property of a body resisting changes in motion / quantity of matter in a body / measure of inertia to changes in motion
weight is the force due to the gravitational field/force due to gravity or gravitational force Allow 1/2 for ‘mass is scalar weight is vector’
(b)(i) arrow vertically down through O tension forces in correct direction on rope.
