Question

a car decreases its speed from 68 km h-1 50 km h-1 in 5 s. Find the acceleration  of the car.
pls help now
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Answer 1

$\pink{ \boxed{\boxed{\begin{array}{cc} \leadsto \bf \: given \\ \\ \rm \to \: initial \: veocity \: \: u = 68 \: km {h}^{ - 1} \\ \\ = \frac{68 \times 1000}{3600} \: m {s}^{ - 1} \\ \\ = 18.89 \: m {s}^{ - 1} \\ \\ \rm \to \: final \: velocity \: \: v = 50 \: km {h}^{ - 1} \\ \\ = \frac{50 \times 1000}{3600} \\ \\ = 13.89 \: m {s}^{ - 1} \\ \\ \rm \to \: time \: \: t = 5 \: s \\ \\ \\ \underline{ \sf \: we \: have \: to \: find \: :} \\ \\ \rm \to \:acceleration \: \: = a \end{array}}}}$

We know that,

$\pink{ \boxed{\boxed{\begin{array}{cc} \sf \: v = u + at \end{array}}}}$

Now , according to the question,

$\blue{ \boxed{\boxed{\begin{array}{cc} \rm \: 13.89 = 18.89 + a \times 5 \\ \\ \rm \implies\:a = \frac{13.89 - 18.89}{5} \\ \\ \rm \implies\:a = - \frac{5}{5} \\ \\ \rm \implies\:a = - 1 \: m {s}^{ - 2} \\ \\ \orange{ \boxed{ \therefore \: \rm \: acceleration \: \: a = - 1 \: m {s}^{ - 2} }}\end{array}}}}$

The negative sign implies that the velocity is decreasing.

Answer 2

Here is your answer

Acceleration = -1ms^-2

Hope it helps you

Thank you.