Question

A ball falls off a table and reaches the ground in
10 s. Assuming g = 10 m/s , calculate its speed
on reaching the ground and the height of the
table.
​

Answer 1

Given

• A ball falls off a table
• Initial Velocity = 0 m/s
• Gravitational Acceleration = 10 m/s²
• Time = 10 sec

To Find

• Height of the table and the velocity of the ball

Solution

● v = u + at [First Equation of Motion]

● v²-u² = 2as [Third Equation of Motion]

✭ Speed of the Ball :

→ v = u + at

→ v = 0 + 10 × 10

→ v = 0 + 100

→ v = 100 m/s

✭ Height of the Table :

→ v²-u² = 2as

→ 100²-0² = 2 × 10 × s

→ 10000 - 0 = 20s

→ 10000/20 = s

→ Height (table) = 500 m

∴ Speed of the ball would be 100 m/s and the Height of the table is 500 m

Answer 2

Answer:

Given :-

• Initial velocity = 0 m/s
• Acceleration due to gravity = 10 m/s
• Time = 10 sec

To Find :-

Speed when hit ground and height of the table

Solution :-

Firstly we will use Newton first law for finding speed

v = u + at

v = 0 + 10 × 10

v = 0 + 100

Hence, speed of Ball is 100 m/s.

Let's find height

Here, we will use Newton third law

v² - u² = 2as

100² - 0² = 2 × 10 × s

10,000 - 0 = 20s

10,000 = 20s

s = 10,000/20

s = 500 m

Hence the height of table is 500 m