Question

a rock thrown down from a bridge has fallen 4t + 4.9t^2 meters.what is the velocity of the apple when t=3?

Don't spam plz...​

Answer 1

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{velocity \: of \: rock \: at \: 3 \: sec =33.4 \: m/s}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{\underline{\bold{Given :}}} \\ \tt: \implies x = {4}t + 4.9 {t}^{2} \\ \\ \tt: \implies Time = 3 \: sec \\ \\ \red{\underline{\bold{To \:Find :}}} \\ \tt: \implies Velocity \: of \: rock \: after \: 3 \: sec =?$

• According to given question :

$\bold{As \: we \: know \: that} \\ \tt: \implies x = 4t + 4.9 {t}^{2} \\ \\ \tt: \implies \frac{dx}{dt} = 4 \times 1 + 2 \times 4.9 \times t^{2 - 1} \\ \\ \tt: \implies \frac{dx}{dt} =4 + 9.8t \\ \\ \tt: \implies v_{(t = 3)} =4 + 9.8 \times 3 \\ \\ \tt: \implies v_{(t = 3)} =4 + 29.4 \\ \\ \green{\tt: \implies v_{(t = 3)} =33.4 \: m/s} \\ \\ \green{\tt \therefore velocity \: of \: rock \: at \: 3 \: sec \: is \: 33.4 \: m/s}$

Answer 2

x = 4t + 4.9 t^2

v = 4 + 9.8 t

at t = 3

v = 4 + 9.8 × 3

v = 33.4 m/s