Question

A truck traveling due north at 50 km/hr turns west and travels at the same speed. what is the change in velocity ?

• A. 50 km/hr north-west
• B. $50\sqrt{2}$ km/hr north-west
• C. 50 km/hr south-west
• D. $50\sqrt{2}$ km/hr south-west

Answer 1

Answer: (D)

$50\sqrt{2}$ km/hr south-west

Answer 2

$\overset{\rightarrow}{\Delta v}$ = $\overset{\rightarrow}{v_{f}}$- $\overset{\rightarrow}{v_{i}}$

$\overset{\rightarrow}{\Delta v}$ = [50 (-$\widehat{i}$) - 50 ($\widehat{j}$)] km/hr

$\overset{\rightarrow}{\Delta v}$= (-50$\widehat{i}$ - 50$\widehat{j}$) km/hr

$|\overset{\rightarrow}{\Delta v}|$ = 50$\sqrt{2}$ km/hr

and direction of $\overset{\rightarrow}{\Delta v}$ = $\frac{\overset{\rightarrow}{\Delta v}}{|\overset{\rightarrow}{\Delta v}|}$ = $\frac{–\widehat{i} - \widehat{j}}{\sqrt{2}}$

$\overset{\rightarrow}{\Delta v}$ = 50 $\sqrt { 2 }$ $\frac{km}{hr}$ south-west