Question

A car initially traveling at 20 kilometers per hour takes 10 seconds to speed up to 70 km/hour. At what rate is it changing speed?

Answer 1

• Initial velocity=u=20km/h
• Final velocity=v=70km/h
• Time=10s=t

Convert speeds to m/s

$\\ \rm\longmapsto u=20\times\dfrac{5}{18}=5.05m/s$

$\\ \rm\longmapsto v=70\times \dfrac{5}{18}=19.4m/s$

$\boxed{\sf Acceleration=\dfrac{v-u}{t}}$

$\\ \rm\longmapsto Acceleration=\dfrac{19.4-5.05}{10}$

$\\ \rm\longmapsto Acceleration=\dfrac{14.3}{10}$

$\\ \rm\longmapsto Acceleration=143m/s^2$