1. The initial speed of the object in m/sec is?1) The initial speed of the object in m/sec is?
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Correct answer is option - 4
Explanation:The initial speed of the object at point A is 20m/sec.
2. From A to B, the acceleration of the object in m/sec^{2} is?
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Correct answer is option - 3
Explanation: In a velocity-time graph, the acceleration is the slope of the graph.
The graph from A to B is a straight line and hence the slope which is (change in ‘y’ value)/ (change in ‘x’ value) = (20 – 20)/ (6 – 0) ==> 0/6 = 0 m/sec^{2}.Therefore the acceleration of the object from point A to B is 0 m/sec^{2}.
3. What is the displacement in ‘meters’ covered by the object from point A to B?
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Correct answer is option - 2
Explanation:Displacement in a velocity-time graph can be calculated by finding the area in between the graph line and the time-axis.In the graph above, the area covered is in the form of a rectangle.
Therefore displacement covered = area covered from point A to B = 20 * 6 = 120m.
4. From point B to point C, what is the direction of the object? Is the object speeding up or slowing down?
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Correct answer is option - 5
Explanation: Since the velocity of the object as shown in the graph from point B to point C is still positive, hence the object is moving in the positive direction.
However, as time is passing by, the velocity is decreasing from point B to C, and hence the object is slowing down.
5. What is the acceleration of the object from point B to C?
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Correct answer is option - 4
Explanation: Acceleration in velocity-time graph = Slope of the line from B to C.
Slope = (change in ‘y’ value)/ (change in ‘x’ value)
This gives: (velocity at C – velocity at B)/ (time at C – time at B)
Therefore, acceleration = (0 – 20)/ (10 – 6) ==> -20/4 = -5m/sec^{2}.
6. The total displacement covered by the object from point A to point C is?
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Correct answer is option - 4
Explanation: The displacement covered from point A to B is the area covered by the rectangle from point A to B with the time-axis = 20 * 6 = 120m. Area covered from point B to C is in the form of a triangle = 1/2 * base * height ==> 1/2 * 4 * 20 = 40m.
This gives the total displacement from point A to C = 120 + 40 = 160m.
7. The object at point C is?
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Correct answer is option - 5
Explanation: The graph is touching the X-axis at point C and the ‘y’ value or the ‘speed value’ at point C is 0 m/sec and this implies that the object stops or is at rest.