velocity with 4. A ball s dropped from a clifi Which of the following grap m a c

Question

velocity with 4. A ball s dropped from a clifi Which of the following grap m a cliff. Which of the following graphs shows the variation of thev c. C d. D 5. The figure below shows the trajectory of a ball thrown up in the air from point A. At C, the highest point of its trajectory a Its velocity is zero and its acceleration acts downwards. b. Both its velocity and acceleration act downwards. c. Its acceleration is zero and its velocity acts downwards. d. Both its velocity and acceleration are zero. 6. Below is shown the motion diagram of an object. Which of the following statements about the position (x), velocity (v) and acceleration (a) is true after it has begun to move and just before it comes to a stop? a. They are all positive. Only x and v are positive. Only and a are positive. d. Only v and a are positive. e. Only x is positive. 7. The acceleration of a marble rolling down a 30P incline is: a. 30 m/s2 b. 9.8 m/s2 c. 8.5 m/s2 d. 4.9 m/s

Explanation / Answer

Ans:

4 and 6 are correct.

5. At the highest point C, the velocity of the ball = 0 m/s that why it's the highest point(otherwise ball would go up more). The acceleration = g acting downards thats how ball reaches zero velocity. The acceleration during free fall is always g acting downwards, it's independent of the velocity of the object.

Option a is correct.

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7)The acceleration of a ball rolling down the incline is given by a = g*sin(theta) where theta = angle of the incline

we are given theta = 30 degrees ==> sin(30) = 0.5 and g = 9.8m/s2

Therefore the acceleration of the ball = 9.8*0.5 = 4.9 m/s2

Option d is correct.

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