A boy pulls a nail from the wall with a string tied to the nail. The string is inclined at an angle of 60o to the wall. If the tension in the string is 4N, what is the effective force used in pulling the nail?
A block of material of volume 20cm-3 and density 2.5gcm-3 is suspended from a spring balance with half the volume immersed in water. What is the reading of the spring balance? (Density of water = 1.0gcm-3).
