Question

1. A particle is moving in a circular path of radius r. The displacement after half a circle

would be:

(a) Zero. (b) π r

(c) 2 r. (d) 2π r

2. A car increases its speed from 20 km/h to 50 km/h in 10 seconds. What is its

acceleration?

3. A body is accelerating at a constant rate of 10m/s2

. If the body starts from rest, how

much distance will it cover in 2 seconds?

4. A particle is moving in a circle of diameter 5m. Calculate the distance covered and the

displacement when it competes 3 revolutions.

5. 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?

6. Distinguish between speed and velocity.

7. Under what condition(s) is the magnitude of average velocity of an object equal to its

average speed?

8. What does the odometer of an automobile measure?

9. What does the path of an object look like when it is in uniform motion?

10. When will you say a body is in (i) uniform acceleration? (ii) non-uniform acceleration?

11. 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?

12. Abdul, while driving to school, computes the average speed for his trip to be 20 km/h. On

his return trip along the same route, there is less traffic and the average speed is 40 km/h.

What is the average speed for Abdul’s trip?



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Answer 1

Answer:

1. 2r

2.

acceleration is given by the change in velocity wrt to time.

acceleration is given by the change in velocity wrt to time.so the total change in velocity is 30km/s.

acceleration is given by the change in velocity wrt to time.so the total change in velocity is 30km/s.acceleration is given by taking care of unit of the time

and distant will be (30×1000)/(10×3600) = 1/12 m/s

3.

The velocity of this body is increasing at a rate of '10 metres per second'. every second. Initial velocity, u=0m/s Time, t=2sAcceleration, a=10m/s2 Using the second equation of motion, s=ut+0.5at^2

=0×2+0.5×10×2×2

×10×2×2=0+20=20m

4. Zero

since it comes at its Initial position

6.

Difference between speed and velocity are as follows

Speed is the rate of change of position of a body in any direction while velocity is the rate of change of position of a body in a particular direction.Speed is a scalar quantity whereas velocity is a vector quantity.

5.

Total distance traveled by farmer in 40s=4×10=40mTotal time taken =2min×20sec=140secTotal number of rounds =40140=3.5If farmer starts from A, then after 3.5 rounds, he reaches to point ′C′. Therefore, displacement =AC.Now, ABCD is a square, then △ABC is a right angled △.Using Pythagoras theorem,AC2=AB2+BC2⇒AC=102+102=200=102AC=10×1.414=14.14mHence, displacement =14.14m

7.

ANSWER

If the speed of the object changing uniformly, magnitude of average velocity of an object equal to its average speed.

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3.