Long Answer Type Questions
34. (a) What is the difference between 'distance travelled by a body and its 'displacement ? Explain with the
help of a diagram.
(b) An ant travels a distance of 8 cm from P to Q and then moves a distance of 6 cm at right angles to PQ.
Find its resultant displacement.
35. Define motion. What do you understand by the terms 'uniform motion' and 'non-uniform motion'? Explain
with examples.
36. (a) Define speed. What is the SI unit of speed ?
(b) What is meant by (i) average speed, and (ii) uniform speed ?
37. (a) Define velocity. What is the SI unit of velocity ?
(b) What is the difference between speed and velocity ?
(c) Convert a speed of 54 km/h into m/s.
38. (a) What is meant by the term 'acceleration' ? State the SI unit of acceleration.
(b) Define the term 'uniform acceleration'. Give one example of a uniformly accelerated motion.
39. The distance between Delhi and Agra is 200 km. A train travels the first 100 km at a speed of 50 km/h. How
fast must the train travel the next 100 km, so as to average 70 km/h for the whole journey?
40. A train travels the first 15 km at a uniform speed of 30 km/h; the next 75 km at a uniform speed of
50 km/h; and the last 10 km at a uniform speed of 20 km/h. Calculate the average speed for the entire train
journey.
41. A car is moving along a straight road at a steady speed. It travels 150 m in 5 seconds :
(a) What is its average speed ?
(b) How far does it travel in 1 second ?
(c) How far does it travel in 6 seconds ?
(d) How long does it take to travel 240 m ?
Answers
Answer:
i dont know all of the answer so i canit give the answer
34. (a) Distance travelled is the actual length of the indirect path covered by the body whereas displacement refers to the straight line path between the initial and final positions.
(b) The ant travels a distance of 8 cm in a straight line from p to q and then moves 6 cm perpendicularly to the line pq. That means it is forming a right angled triangle. So, by using Pythagoras theorem we can find the third side.
... Hence, the displacement of the ant = √100 = 10 cm, which is the longest side of a triangle.
35. Motion- If the position of an object is changing with respect to it's surroundings, then it is said to be in motion.
Uniform motion- If an object covers equal distances in equal time intervals, it is said to be moving with uniform speed.
Example- If the speed of a car is 10 m/s, it means that the car covers 10 meters in one second. The speed is constant in every second.
Non uniform Motion- If an object covers unequal distances in equal time intervals, it is said to be moving with non- uniform motion.
Example- A horse running in a race.
36. (a) Speed- the rate at which somebody/something moves or travels.
The SI unit of speed is m/s.
(b) (1) The average speed of an object is the total distance traveled by the object divided by the elapsed time to cover that distance.
(2) if an object is traveling in such a way that it covers the same distance for each interval of time it is traveling, then it is said to be traveling with uniform speed.
37. (a) The displacement taht occurs in unit time is called velocity.
The SI unit of velocity is m/s.
(b) Speed is the rate at which an object covers distance in a particular time. ... Velocity is the displacement traveled by a body per unit time. It is a vector quantity.
(c) 15 metres per second.
38. (a) The rate of change of velocity is called acceleration.
The SI unit of acceleration is m/s².
(b) If the velocity changes by equal amounts in equal time intervals, the object is said to be in uniform acceleration.
Example- One of the common examples of uniformly accelerated motion is freely falling bodies.
39. Answer is in attachment.
40. 40km/hr is average speed of the train.
41. (a) speed=d/t
s=150/5
s=30m/s
(b) t=1
d=sxt
=30x1=30
(c) 30x6=180
(d) t=d/s
=240/30
=8s
