Title: To determine the coefficient of static friction between two surfaces
Objective: To investigate the relationship between the mass of load and the length of spring and the coefficient of static friction between two surface.
Part 1: The relationship between the mass of load and the length of spring
Apparatus and materials: Retort stand, spring, Slotted masses 200g with hanger, Meter rule

Setup: Procedure:
1. One of the end of the spring is hooked on the retort stand.
2. The hanger with a 20g slotted mass is hang at the other end of the spring.
3. The length l1 of the spring has been measured, mass m1 of the load are recorded.
4. The mass m1 is increase and corresponding length l1 of the spring has been measured.
5. Data of l1 and m1 is tabulated.
6. Graph of l1 against m1is plotted.

Part 2: The coefficient of friction between two surfaces
Apparatus and Materials: smooth plank as inclined plane, Retort stand, wooden blocks, Electronic balance, spring, Protractor, Pendulum bob, Thread, Plasticine.
Setup:

Theory: If the wooden block is being displaced down the inclined plane, the block will return to its original position when released because the net force up the plane exceeds the limiting friction down the plane. The downward displacement is being reduced gradually until a stage where the block stays stationary when released. At this point, the force up the plane equalized the limiting friction down the plane. If T is the tension of the spring, F is the limiting friction, and µ is the coefficient of static friction, then
T- mg sin θ = F
T- mg sin θ = µ mg cos θ
If T = m’g, where m’ = mass equivalent to tension T, then m’g – mg sin θ = µ mg cos θ m’ = m( µ cos θ + sin θ) Procedure:
1. The mass of wooden block with a smooth surface has been weigh. The mass of wooden block is recorded.
2. Retort