For a car driving at a steady speed around a perfectly circular track which stat
ID: 1600098 • Letter: F
Question
For a car driving at a steady speed around a perfectly circular track which statement is true? a) The car's acceleration a zero. b) If there is so friction, the acceleration is outward. c) The net force on the car is zero. d) Both the acceleration and net force on the car point inward. e) Both the acceleration and net force on the car point outward. The net force exerted on a large box is observed over a 10-s interval and is shown in the graph in the figure. What is the average power delivered to the box over this time interval? a) 0.0 W b) 1.3 W c) 2.5 W d) 2.2 W e) 5.0 W You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is a) speeding up b) slowing down c) changing direction d) speeding up and changing direction e) slowing down and changing directionExplanation / Answer
Q4) The car is in steady circular motion. So only function of the net force acting on it is to provide the necessary centripetal force. Therefore, the net force and the corresponding acceleration point inwards (towards the centre).
Ans: Option (d)
Q5) Power is obtained as the ratio of work done to the time taken. Here, work can be calculated as the area under the F-x graph which gives the area of the triangle with base 10 and height 5 (numerically).
Therefore, W = (1/2) × 10 × 5 = 25 J
Power, P = W / t = 25 / 10 = 2.5 W
Ans: Option (c)
Q6) Train is on horizontal track. If it were moving steadily, the luggage would be in equilibrium. But as it is moving directly towards the front, it means that it has got an acceleration (due to pseudo force) brought about by the deceleration of the train. That is, the train is just slowing down.
Ans: Option (b)
[If the train accelerates (or speeds up), the luggage will move backwards. If the train takes a turn, the luggage will move to the outer wall of the train ( if train turns to right, then luggage moves to the left and vice versa].