Question

1.
A ball is projected vertically up with speed of
20 m/s The distance travelled in 4th second is
-(1) 15m
(2) 5 m
(3) 20m
(4) 40m​

Answer 1

5m because speed increase with height

Answer 2

Answer:

${\bold{\therefore S_{4}=-15\:m}}$

Explanation:

$\huge{\bold{\underline{\underline{SOLUTION-}}}}$

• In the given question information given about a ball which is thrown upward with a velocity of 20 m/s.

• We have to find the distance travelled in 4th second.

$\underline \bold{Given : } \\ \implies Initial \: velocity(u) = 20 \: m/s \\ \\ \implies Time = 4th \: second \\ \\ \implies Acceleration(a) = g = -10 \: m /{s}^{2} \\ \\ \underline \bold{To \: Find : } \\ \implies Distance \: travelled \: i \: 4th \: second = ?$

• According to given question :

$\bold{For \: nth \: sec \: displacement: } \\ \implies S_{n} = u + \frac{1}{2} a(2n - 1) \\ \\ \bold{For \: 4th \: second \: displacement : }\\ \implies S_{4} = 20 + \frac{1}{2} \times (- 10)(2 \times 4 - 1) \\ \\ \implies S_{4} = 20 + \frac{1}{2} \times (- 10)(8 -1 ) \\ \\ \implies S_{4} = 20 + \frac{1}{ \cancel2} \times \cancel{ - 10} \times 7 \\ \\ \implies S_{4} = 20 - 35 \\ \\ \bold{\implies S_{4} = - 15 \: m}$