Question

Thinking Critically TC-5 Name Section Handout 2.1 THINKING CRITICALLY: Evaluating Questions and Answers To so the problem below, you must write a clear and convincing justification for accepting one of the possible ist choices as the best of most appropriate and for rejecting each of the other choices as less appropriate Your reasons for rejecting choices are just as important as your reasons for choosing the best answer The graph depicts the velocity of a moving object. Which of the following events is most likely shown by the graph? a aball rolling down an inclined plane and then across a level floor b a car driving off a cliff and falling into a deep canyon c a weight dropping from above a lake, hitting the water, and then falling through the water d. ball thrown upward and landing on the flat roof of a building e. a ball thrown by one person and caught by a second person

Answer 1

2.1

THE VELOCITY TIME GRAPH SHOWS THAT SLOPE OF IT WILL GIVE ACCELERATION

SO FOR THE SEGMENT WHEN VELOCITY IS INCREASING, IT MEANS THE BODY IS

ACCELERATING, AFTERWARDS THE VELOCITY SUDDENLY DROPS DUE TO A SUDDEN IMPACT

AND AFTERWARDS THE RATE OF CHANGE OF CHANGE OF VELOCITY IS NOT SO STEEP AS THAT THE EARLIER CASE, HENCE ITS ACCELERATION IS MUCH SLOWER DUE TO PRESENCE OF RESISTIVE FORCES.

a. This is not the possible case because while rolling down it will have its speed increasing so it will have positive acceleration

but on reaching the level floor the speed will not change suddenly due to friction, it will change gradually

b. A car when driving of the cliff will have increasing speed or it may have constant speed, sot the first segment can be inclined to time axis or can be parallel to the time axis.

c. A weight dropping, will have increasing speed and when it hits the lake, the speed suddenly reduces due to impact, and while going inside the water, due to viscous and buoyant forces, the speed decreases gradually.

d. When a ball is thrown upwards it speed decrease upto the maximum height, so it will retard, not accelerate.

e. When a ball is thrown by one person, it follows a parabolic path and it ascends first then it descends.

While ascending its speed decreases then increases.

So the correct case of the graph is the case c.