Find the displacement between 10 to 20 s from the graph given below. Class 9

Find the displacement between 10 to 20 s from the graph given below. Class 9

Question 1.

Find the displacement between 10 to 20 s from the graph given below. Class 9

Answer:

Displacement between 10 to 20 s = area of ABDE

= area of rectangle ACDE + area of triangle ABC

= AE × CA + 1/2 × CA × BC

= 5 × 10 + 1/2 × 10 × 5

= 75 m

Question 2.

A car is moving with velocity of 54 km/h and brakes are applied to cause an acceleration of - 4 m/s². How much distance car will travel before it stops? Class 9

Answer:

Initial velocity, u = 54 km/h = 15 m/s (54 × [latex]\frac{5}{18}[/latex])

Final velocity, v = 0 and acceleration = - 4 m/s²

v² = u² + 2 as

Body comes to rest v = 0

0 = (15)² + 2 (-4) s ⇒ 225 = 8 s ⇒ s = 28.1 m