Question

Write the equations of motion when an object falls freely towards the earth or is thrown vertically upwards. Write along with their units.

Answer 1

Step 1: A freely falling body always experiences a downward acceleration g which we call acceleration due to gravity.

Thus, acceleration of the freely falling body $g=9.8m/s2$

The initial speed of that body “u=0”

The final velocity of that body is ‘v’

The height of the body is ‘h’

Equations of motion:

(i) $v=gt$

(ii) $S=\frac{1}{2}g{t}^2$

(iii) $v^2=2gh$

Step 2: The equations of motion when an object is thrown vertically upwards:

For a vertically thrown object, the gravitational force will act downwards. That is why the object will experience a negative acceleration and g= -9.8 m/s ²

Here, the Initial speed of that body (u) is not zero.

i) $v=u–gt$

ii) $h=ut-\frac{1}{2}gt²$

iii) $v²-u²=2gh$