Question

An object starting from rest travels 20m in first 2 s and 160m is next 4 s.what will be the velocity after 7 s from the start?

Getting Bored
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Answer 1

Answer:

Sus Means

Explanation:

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Answer 2

❐ FULL EXPLANATION:

.

$\underline{In \: First \: 2 \: Seconds },$

• $s = 20m$
• $t = 2 s$
• $u = 0m {s}^{ - 1}$

$\underline{As \: We \: Know \: That},$

• $s = ut + \frac{1}{2} a {t}^{2} \: \: \: ...(By \: 2nd \: law \: of \: motion)$

$\underline{We \: Get},$

$\implies 20 = (0)2+ \frac{1}{2} a {(2)}^{2}$

$\implies 20 = 0+ \frac{1}{ \cancel{2}} a {( \cancel{4})}$

$\implies 20 = 2a$

$\implies a = 10m {s}^{ - 2}$

$\underline{As \: We \: Know \: That},$

• $v = u + at \: \: \: ...(By \: 1st\: law \: of \: motion)$

$\underline{We \: Get},$

$\implies v = 0 + 10(2)$

$\implies v = 20m {s}^{ - 1}$

$\underline{So},$

• $The \: Velocity \: After \: 2s \: is \: 20 {ms}^{ - 1} .$

$\underline{In \: First \: 4 \: Seconds },$

• $s_1 = 160m$
• $t_1 = 4 s$
• $u_1 = 20m {s}^{ - 1}$

$\underline{As \: We \: Know \: That},$

• $s_1 = u_1t_1 + \frac{1}{2} a_1 {(t_1)}^{2} \: \: \: ...(By \: 2nd \: law \: of \: motion)$

$\underline{We \: Get},$

$\implies 160 = (20)4+ \frac{1}{2} a_1 {(4)}^{2}$

$\implies 160 = 80+ \frac{1}{ \cancel{2}} a_1 ( \cancel{16} )$

$\implies 160 - 80 = 8 a_1$

$\implies 160 - 80 = 8 a_1$

$\implies 8 a_1 = 80$

$\implies a_1 = \frac{80}{8}$

$\implies a_1 = 10 {ms}^{ - 1}$

$There \: is \: equal \: Acceleration.$

$\underline{So},$

• $There \: is \: Uniform \: Acceleration.$

$\underline{As \: We \: Know \: That},$

• $v = u + at \: \: \: ...(By \: 1st\: law \: of \: motion)$

$\underline{We \: Get},$

$\implies v = 0 + 10(7)$

$\implies v = 70 {ms}^{ - 1}$

$\underline{So},$

• $The \: Velocity \: After \: 7s \: is \: 70 {ms}^{ - 1} .$

❐ REQUIRED ANSWER:

.

• $\underline{The \: Velocity \: After \: 7s \: is \: 70 {ms}^{ - 1} }.$