Class 9 chapter 7 Motion

Class 9 chapter 7 Motion

• Q: What is the reference point used to describe the position of an object called? A: It is called the origin.
• Q: What is the shortest distance measured from the initial to the final position of an object known as? A: It is known as displacement.
• Q: Can the magnitude of displacement be zero? A: Yes, if the final position of an object coincides with its initial position, the displacement is zero, even if the distance covered is not zero.
• Q: What device is fitted in automobiles to measure the distance they have travelled? A: An odometer.
• Q: When is an object said to be in uniform motion? A: An object is in uniform motion when it covers equal distances in equal intervals of time.
• Q: What is the SI unit of speed? A: The SI unit of speed is metre per second (represented as m s–1 or m/s).
• Q: How is the average speed of an object calculated? A: Average speed is obtained by dividing the total distance travelled by the total time taken.
• Q: How does velocity differ from speed? A: Velocity is the speed of an object moving in a definite direction.
• Q: What physical quantity measures the change in the velocity of an object per unit time? A: Acceleration.
• Q: What is the SI unit of acceleration? A: The SI unit of acceleration is metre per second squared (m s–2).
• Q: What does a straight line on a distance-time graph indicate about an object's motion? A: It indicates that the object is moving with uniform speed.
• Q: What quantity is represented by the area enclosed below a velocity-time graph? A: The area represents the distance (or magnitude of displacement) travelled by the object.
• Q: What are the three equations of motion used for an object moving with uniform acceleration? A: The three equations are $v = u + at$, $s = ut + ½ at^2$, and $2as = v^2 – u^2$.
• Q: What is it called when an object moves in a circular path with a constant speed? A: It is called uniform circular motion.