• SLC Science
  • Gravitational force
    • Law of gravitation
    • Acceleration(g)
    • Free fall
    • Numerical Problems
  • Pressure
    • Def.Pressure
    • Principles
    • Upthrust
    • Numerical Problems
  • Heat
    • Heat Energy
    • Anomalous expansion of water
    • Specific heat capacity
    • Numerical Problems
  • Electricity
    • Electricity
    • Fuse
    • Faraday'sPrinciple
    • Transformer
    • Numerical Problems
• SLC English
• SLC Mathematics
• SLC Opt.Maths
• +2 Science
  • Wave Motion

Acceleration due to gravity(g)

Definition: Acceleration produced on falling body due to force of gravity is called accelecation due to gravity.
It is denoted by g. And its unit is m/sec².

Acceleration due to gravity
• For Earth g = 9.8m/sec ²
  
• For Moon g = 1.67m/sec ²
  
• For Jupiter g = 25 m/sec ²

Q. What do you mean by acceleration due to gravity of earth is 9.8 m/sec²?
→ This means that the velocity of falling body under the gravity of earth increases per second 9.8 m/sec.

Acceleration due to gravity 'g' depends on
• the mass of earth and
• distance from the center of earth.

By the formula
Acceleration due to gravity g = $\frac{\mathrm{GM}}{\mathrm{R²}}$ where M is mass of earth, R is radius of earth.

• From the above we can say that the 'g' is inversly proportional to the square of radius (R²).

As we know radius of earth is not uniform, it is greater at Equator and small at poles. Therefore 'g' has greater value at poles and 'g' has smaller value at Equator. And on average is taken as 9.8 m/sec².

• From this we can say that the gravitational acceleration doesnot depend on mass of body therefor if two object having different mass is droped from same height together both object reached ground same time.

Q. Suppose Earth is compressed to equal volume to moon, then what's effect on gravitational acceleration?
→ If earth is compressed to volume equal to moon, then radius goes on decreasing there for gravitational acceleration increased about 14 times.
Q. Acceleration due to gravity has no relation with the free falling object's mass. Justify this with one example?
→ All free falling objects have equal gravitaional acceleration, don't have any relation to falling object's mass. On moon surface a coin and feather fall together because there no air and hence free falling occur.
Q. Suppose an object is droped from same height at Equator and poles one after another then at which place object reached fast, why?
→ Due to greater value of 'g' at poles object reached fast to the ground at poles and due to smaller value of 'g' at equator object reached slowly to the ground at equator.
Acceleration due to gravity at top of the hill
We can write formula as g =$\frac{\mathrm{GM}}{\mathrm{(R+h)²}}$
where 'h' is height of Hill

• From this it is clear that the 'g' has smaller value as we go top of the hill.

Weight:-Weight of an object is the attraction force towards center applied by Earth.
By the formula, Weight (w) = mg
where m is mass of object and g is acceleration due to gravity

• From this we can say that the weight of the object i.e. force of attraction towards center of earth is changed with respect to places as it depend on 'g' which changed as place changed.

Q. Weight of same object is higher at poles but lesser at equator, why?
→ Due to greater value of 'g' at poles more weight(w=mg) of object at poles and due to smaller value of 'g' at equator less weight of object at equator.

• Similarly we can say that the weight of the object is more at sea level or tarai and object has less weight at top of the hill.

All objects at the condition of free fall have same gravitational acceleration (g).
• This signifies that if a large and small stone is dropped from same height at same time both reached together at the ground
• Due to negligible resistance of air on stone, both stone fall freely and hence both have same gravitational acceleration (g) and reache same time at ground.
• Due to abscense of air at moon all objects (feather and coin) fall freely and reached same time to the ground.
• Due to resistance of air parachute fall slowly and uniformly on earth surface. Therefore possible to jump from aeroplane without danger. But it is danger on moon surface because there is no air.