EXAMPLE 3.2 If two objects of masses \( 2.5 kg \) and \( 100 kg \) experience the same force \( 5 N \), what is the acceleration experienced by each of them? Solution From Newton's second law (in magnitude form), \( F = ma \) For the object of mass \( 2.5 kg \), the acceleration is \( a=\frac{F}{m}=\frac{5}{2.5}=2 m s ^{-2} \) For the object of mass \( 100 kg \), the acceleration is \( a=\frac{F}{m}=\frac{5}{100}=0.05 m s ^{-2} \)

Question

EXAMPLE 3.2 If two objects of masses \( 2.5 kg \) and \( 100 kg \) experience the same force \( 5 N \), what is the acceleration experienced by each of them? 

Answer 1

From Newton’s second law (in magnitude form), F = ma

For the object of mass 2.5 kg

The acceleration is a =F/m = 5/2.5 = 2 ms^-2

For the object of mass 100 kg

The acceleration is a= F/a = 5 /100 = 0.05 ms^-2

When an apple falls, it experiences Earth’s gravitational force. According to Newton’s third law, the apple exerts equal and opposite force on the Earth. Even though both the apple and Earth experience the same force, their acceleration is different. The mass of Earth is enormous compared to that of an apple. So an apple experiences larger acceleration and the Earth experiences almost negligible acceleration. Due to the negligible acceleration, Earth appears to be stationary when an apple falls.