Graphical Representation of Motion | Motion | Assessment | English | Grade 9

What does the slope of a distance−time graph represent?

• Distance

• Time

• Speed

• Displacement

Answer explanation

The slope of distance−time graph represents speed.

Look at this graph of two children A and B running together. Who do you think is running faster?

• Both are running at the same speed.

• A

• B

• None of the above

Answer explanation

Both reach their destination at the same time. But B takes less time to cover the same distance. Hence B is running faster.

Here is a displacement−time graph of a car. P, Q, R, S and T are five parts of the journey as shown in the graph. In which two parts do you think the speed of the car would be same?

• In part R and part P

• In part Q and part S

• In part P and part Q

• All of the above

Answer explanation

Speed = Displacement /time There two parts Q and S, where displacement = 0. So, in part Q and part S, Speed = 0/time taken = 0 Hence, option 2 is correct

What is the unit of the physical quantity represented under the area velocity−time graph?

• m/s²

• m

• m/s

• m²

Answer explanation

The physical quantity measured here is displacement. Hence, option 2 is correct.

Which of the following graph shows non−uniform acceleration?

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Answer explanation

Option 3 shows non−uniform acceleration.

In this velocity−time graph, what will be the displacement between 10 to 15 seconds and acceleration between position B and E.

• S= 150 m a = − 4 m/s²

• S= 150 m a = 4 m/s²

• S= 125 m a = 20 m/s²

• S= 125 m a = −20 m/s²

Answer explanation

Displacement= area of rectangle ABCD + Area of triangle BCE = (5 × 20) + 1/2 × 5 ×20 = 150 m Acceleration between E & B = (20−40)/(15−10) = −20//5 = − 4 m/s²

Draw a velocity- graph from the following information. A ball from rest at the top of a hut moves with constant acceleration for 5 seconds and attains a velocity of 15m/s. After that it travels at constant speed for 15 seconds. After which it decelerates for 10 seconds at a constant rate of 1 m/s².Then it rolls for 20 seconds at a constant speed.

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Answer explanation

Velocity of the ball in the first 5 seconds = 15 m/s Hence, mark the coordinates (5, 15) on x and y axis respectively. Then, there is constant speed for 15 seconds, so mark the coordinates (20, 15) on x and y axis respectively. Then it accelerates at 0.5 m/s² for 10 seconds, so the speed comes to 0.5 × 10 = 5 m/s Mark the coordinates (30,5) Finally, there is constant speed for 20s, so mark the coordinates (50,5)