Page No 100:
Question 1:
An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example.
Page No 100:
Question 2:
A farmer moves along the boundary of a square field of side 10 m in 40 s. What will be the magnitude of displacement of the farmer at the end of 2 minutes 20 seconds?
Page No 100:
Question 3:
Which of the following is true for displacement?
(a) It cannot be zero.
(b) Its magnitude is greater than the distance travelled by the object.
Page No 100:
Question 10:
An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the earth?
Page No 102:
Question 2:
Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?
Page No 102:
Question 4:
What does the path of an object look like when it is in uniform motion?
Page No 102:
Question 5:
During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, 3 × 108 m s−1.
age No 103:
Question 1:
When will you say a body is in (i) uniform acceleration? (ii) non-uniform acceleration?
Page No 107:
Question 1:
What is the nature of the distance−time graphs for uniform and non-uniform motion of an object?
Page No 107:
Question 2:
What can you say about the motion of an object whose distance−time graph is a straight line parallel to the time axis?
Page No 107:
Question 3:
What can you say about the motion of an object if its speed−time graph is a straight line parallel to the time axis?
Page No 107:
Question 4:
What is the quantity which is measured by the area occupied below the velocity−time graph?
Page No 110:
Question 3:
A trolley, while going down an inclined plane, has an acceleration of 2 cm s−2. What will be its velocity 3 s after the start?
Page No 110:
Question 4:
A racing car has a uniform acceleration of 4 m s−2. What distance will it cover in 10 s after start?
Page No 110:
Question 5:
A stone is thrown in a vertically upward direction with a velocity of 5 m s−1. If the acceleration of the stone during its motion is 10 m s−2 in the downward direction, what will be the height attained by the stone and how much time will it take to reach there?
Page No 112:
Question 1:
An athlete completes one round of a circular track of diameter 200 m in 40 s. What will be the distance covered and the displacement at the end of 2 minutes 20 s?
Page No 112:
Question 2:
Joseph jogs from one end A to the other end B of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph’s average speeds and velocities in jogging (a) from A to B and (b) from A to C?
Page No 112:
Question 3:
Abdul, while driving to school, computes the average speed for his trip to be 20 km h−1. On his return trip along the same route, there is less traffic and the average speed is 30 km h−1. What is the average speed for Abdul’s trip?
Page No 112:
Question 4:
A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 m s−2 for 8.0 s. How far does the boat travel during this time?
Page No 112:
Question 5:
A driver of a car travelling at 52 km h−1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h−1 in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?
age No 112:
Question 6:
Fig 8.11 shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:
(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d)How far has B travelled by the time it passes C?
Page No 113:
Question 7:
A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 m s−2, with what velocity will it strike the ground? After what time will it strike the ground?
Page No 113:
Question 8:
The speed-time graph for a car is shown is Fig. 8.12.
Fig. 8.12
(a) Find out how far the car travels in the first 4 seconds. Shade the area on the graph that represents the distance travelled by the car during the period.
(b) Which part of the graph represents uniform motion of the car?
Page No 113:
Question 9:
State which of the following situations are possible and give an example for each of these:
(a) an object with a constant acceleration but with zero velocity.
(b) an object moving in a certain direction with an acceleration in the perpendicular direction.