Question

Solve this problem... Really urgent ​

Answer 1

`\boxed{\sf Time \ taken = 15 \ minutes}`

Given:

Initial speed (u) = 65 km/h

Final speed (v) = 85 km/h

Acceleration (a) = 80 km/h²

To Find:

Time taken for car to achieve a speed of 85 km/h in minutes

Explanation:

`\sf From \ equation \ of \ motion:`

`\boxed{ \bold{v = u + at}}`

By substituting value of v, u & a we get:

`\sf \implies 85 = 65 + 80t`

Substract 65 from both sides:

`\sf \implies 85 - 65 = 65 - 65 + 80t`

`\sf \implies 20 = 80t`

`\sf \implies 80t = 20`

Dividing both sides by 80:

`\sf \implies \frac{ \cancel{80}t}{ \cancel{80}} = (20)/(80)`

`\sf \implies t = \frac{2 \cancel{0}}{8 \cancel{0}}`

`\sf \implies t = \frac{ \cancel{2}}{ \cancel{2} * 4}`

`\sf \implies t = (1)/(4) \: h`

`\sf \implies t = (1)/(4) * 60 \: minutes`

`\sf \implies t = 15 \: minutes`

So,

Time taken for car to achieve a speed of 85 km/h in minutes = 15 minutes