Question

4. A ball is thrown up with a velocity of 20 ms. What is the time of flight, neglecting air resistance?​

Answer 1

Velocity of the ball through which it is thrown = 20 \: m \: s {}^{ - 1}=20ms

−1

Acceleration due to gravity (g)

= 10 \: m \: s {}^{ - 2}=10ms

−2

To find:-

The time of the flight, neglecting the air resistance.

Solution:-

When the body comes back to the initial position, the displacement s = 0

We know that,

s = ut – 1/2gt^{2}

2

\Longrightarrow⟹ s = ut – 1/2gt^{2}

2

\Longrightarrow⟹ 0 = ut – 1/2gt^{2}

2

\Longrightarrow⟹ ut = 1/2gt^{2}

2

t = 2u/g. Here ‘t’ is the time of flight, i.e., {t_a} + {t_d}t

a

+t

d

Therefore, Time of flight, t =

\frac{2 \times 20}{10} = 4s

10

2×20

=4s

Thus, time of flight neglecting the air resistance = 4s.