Question

248 / H. M. Science For Class 9 Very Short Answer Type Questions 1. What is motion ? 2. What is displacement ? 3. A small toy was thrown vertically upward. It went upto height h and then return to earth. How much distance did it travelled? What was its displacement ? [Ans. 2h, zen 4. A body is moving with a uniform velocity of 10 m/s. What will be the distance travlled by (Ans.spot body of 2 s. 5. In speed and velocity, which quantity is vector ? 6. What is the unit of speed ? 7. Write first equation of motion, 8. In which type of motion a body travels unequal distances in equal intervals of time ? 9. What is acceleration ? 10. What is the unit of acceleration ? 11. Write the formula for calculating velocity. 12. The velocity of a particle is constant. What is its acceleration ? 13. A particle moves on a straight line from the point A to the point B and then returns from to the point C, where it stops. (see fig.) 5 cm B​

Answer 1

Answer:

change position with time is called motion

displacement is the measurement of the length of shortest path from the initial poit to final point

Answer 2

1  Movement of any object from one position to another position with respect to the observer is called as Motion. Motion Along a Straight Line: When an object moves along a straight line, the motion of the object is called rectilinear motion. For example; motion of a car on highway.

2 Displacement:–The shortest distance between the initial position and the final position of a moving object in the given interval of time from initial to the final position of the object is known as the displacement of the object.

3 : As the toy is thrown vertically upward and it went to height h. The distance travelled by the toy will be 2h because it travels the same distance to return on earth surface and displacement will be 0 because the toy return its position back so, no displacement takes place.

4 Velocity= Distance/ time.

Or Distance = velocity × time

So , Distance covered in 2 second when a body is moving with 10 m/s is equal to 10× 2 = 20 m.

5 Speed is a scalar quantity and does not keep track of direction; velocity is a vector quantity and is direction aware.

6   metre per second

7 (V f =Vi + at)

8 Non-Uniform Motion

9 Acceleration: It is a measure of the change in the velocity of an object per unit time. Acceleration can be caused either by change in direction of motion or change in speed or both.

10  (m/s2).

11  Velocity (v) is a vector quantity that measures displacement (or change in position, Δs) over the change in time (Δt), represented by the equation v = Δs/Δt. Speed (or rate, r) is a scalar quantity that measures the distance traveled (d) over the change in time (Δt), represented by the equation r = d/Δt.

12 When the velocity of a particle is constant the acceleration will be zero.

13 so the distance is nothing but 15m ok but the displacement is 10-5=5 and 5 is the displacement

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