Practical exercise 2 and 3:

Aim of Practical exercises 3.2 and 3.3:

To demonstrate the change in the gravitational force with the change of the distance or masses of the bodies. To demonstrate that the gravitational acceleration (g) =(G MEarth)/(REarth)2. The activities are individual. The discussion of the results is for the whole class.

Instructions for the teacher:

In exercise 3.2, in the formula F = G (m1M2/d2), m1 is the mass of the student, М2 is the mass of the Earth, and d is the distance from the centre of the Earth to the student, i.e. d = 6.38 х 106 m in part (a) and d = 6.39 х 106 m in part (b).

Answer (a) F = 491.81 N (or approximately 492 N) ; (b) F = 490.28 N (or approximately 490 N).

Start a discussion about the small difference in the force at sea level and at height of 10 km. Compare it with the answer of exercise 3.3. (a) and draw students’ attention to the fact that actually g = (G MEarth)/(REarth)2.