Question

If the force experienced by a body of unit mass is gravitational field strength, find the gravitational field strength on the surface of the earth

Answer 1

Are weight, gravitational force and gravity the same thing?"Almost.Gravitational force (or pull or attraction) and gravity mean the same - the force of attraction between 2 (or more) masses.Sometimes the terms are use in a general descriptive sense. Sometime they are used to mean actual values (usually force in newtons).But 'weight' is specifically the gravitational force on an object pulling it towards a nearby planet or moon (usually the earth). So if you are on or near the earth, your weight is the gravitational pull of the earth on you. If you are on or near the moon, your weight is the gravitational pull of the moon on you._______________________Gravitational field strength (symbol g) is a number. It measures how strong gravity is. It is defined as the gravitational force experienced by a 1kg mass.. (Or you could say it is the gravitational force per kg.)On earth g = 9.8 N/kg approximately. So for example:If mass = 1kg, the weight = 9.8NIf mass = 2kg, the weight = 2 x 9.8 = 19.6NThis is where the formula W=mg comes from.________________________On the moon, gravity is a bit weaker. g = 1.6N/kg approx. So on the moon:If mass = 1kg, the weight = 1.6NIf mass = 2kg, the weight = 2 x 1.6 = 3.2N________________________If something falls, ignoring air resistance, it accelerates due to gravity. The force causing the acceleration is the weight. The acceleration is called gravitational acceleration or acceleration due to gravity or the acceleration of free fall. It is measured in m/s^2 (like all accelerations).However, you probably know the formula F = ma. If we use this we can calculate acceleration.E.g. a 2kg mass (weight =19.6N) falls. Find the acceleration.F=maBut F = weight so19.6 = 2aa =9.8m/s^2You see gravitational acceleration is the same number as gravitational field strength. This is always true. Remember W=mg, so F=ma becomes mg=ma. The mass cancels and we get a=g.So you will find gravitational field strength (for earth) sometimes quoted as 9.8N/kg or as the acceleration value of 9.8m/s^2. They tell you the same thing. In fact you can show that the unit N/kg is equivalent to the unit m/s^2

Answer 2

Gravitational feild strength at surface of Earth = g = GM/R²
Where..,
G = Universal Gravitation constant
M = Mass of Earth
R = Radius of Earth

After substituting values we will get g = 9.8m/s²