Chapter 5, Problem 90A

To determine

Length of the vector.

Answer to Problem 90A

Length of vector is 10mm to represent velocity of 20 m/sec.

Explanation of Solution

Given:

15 mm long vector represent a velocity of 30 m/sec

Formula used:

If the length of vector is directly proportional to velocity.Then the relation between length and velocity will be,

  $\frac{l_1}{v_1}=\frac{l_2}{v_2}$

Calculation:

Here,

  $\begin{array}{l}{l}_1=15\text{ mm, }{v}_1=30\text{ m/sec}\\ v_2=20\text{ m/sec}\end{array}$

Now, putting the value of $l_1,v_1\text{ and }{v}_2$ in the above relation.

  $\begin{array}{c}\frac{15}{30}=\frac{l_2}{20}\\ l_2=\frac{15\times 20}{30}\\ =10\text{ mm}\end{array}$

Conclusion:

Therefore, length of vector is 10 mm to represent velocity of 20 m/sec.