Answer:
[tex] \boxed{\sf Time \ taken = 15 \ minutes} [/tex]
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
Step-by-step explanation:
[tex]\sf From \ equation \ of \ motion:[/tex]
[tex] \boxed{ \bold{v = u + at}}[/tex]
By substituting value of v, u & a we get:
[tex] \sf \implies 85 = 65 + 80t[/tex]
Substract 65 from both sides:
[tex] \sf \implies 85 - 65 = 65 - 65 + 80t[/tex]
[tex] \sf \implies 20 = 80t[/tex]
[tex] \sf \implies 80t = 20[/tex]
Dividing both sides by 80:
[tex] \sf \implies \frac{ \cancel{80}t}{ \cancel{80}} = \frac{20}{80} [/tex]
[tex] \sf \implies t = \frac{2 \cancel{0}}{8 \cancel{0}} [/tex]
[tex] \sf \implies t = \frac{ \cancel{2}}{ \cancel{2} \times 4} [/tex]
[tex] \sf \implies t = \frac{1}{4} \: h[/tex]
[tex] \sf \implies t = \frac{1}{4} \times 60 \: minutes[/tex]
[tex] \sf \implies t = 15 \: minutes[/tex]
So,
Time taken for car to achieve a speed of 85 km/h in minutes = 15 minutes
