Page 1 :
Quide ,, , CHAPTER 1, , MOTION, , ‘A, MULTIPLE CHOICE QUESTIONS:, , 1. The motion along a straight line is called, , (a) circular (6) linear (c) vibratory (d) rotatory, 2. The speedometer is a device which measures, , (a) acceleration (b) average speed, , ©) instantaneous speed (d) average velocity, 3. The odometer is a device which is used to record the *, , (a) speed (G) distance (c) acceleration (d) velocity, , 4. Ifa body comes to rest, its:, (a) u=90 v=0 (c) t=0 (d) none of these, , 5. A-v-t graph parallel to x-axis, represents, (a) uniform motion of the object (b) rest position of the object, (c) non-uniform motion of the object (d) accelerated motion of the object, , 6. If the v-t graph of a body is parallel to x-axis, then its acceleration is, (a) negative (b) positive ¢) zero (d) variable, , 7. Incircular motion the : :, (a) direction of motion is fixed direction of motion changes continuously, (c) velocity is constant (d) acceleration is zero, , “S.A dt graph of two cars is as shown. State which is correct. ¥, - (a) Car B moves faster than car A, , Car A moves faster than car B i, (c} Car A and car B moving with, (d) None of these same speed, , 9. Abady increases its speed from 20 m/s to 50 m/s in 10 seconds, its acceleration is:, (a) 0.3 m/s? (b) 30 m/s? (¢) 3 m/s? (d) 18 m/s?, , ANSWERS : | (b), 2 (c), 3 (b), 4 (b), 5 (a), 6 (c), 7 (b), 8 (b), 9 (Cc)
Page 2 :
Sol:, , Sol:, , Sol:, , Sol:, , Sol:, , as, , (Cc,, , Sol:, , Sol:, , Osecondary Science Ix, , estions, , Very Short Answer Type Qu | |, ector quantities—dista, , Which of the following are v ., displacement, mass, acceleration: ariitles., , i ctor qu, Velocity, displacement and acceleration are Ve q, , nce, speed, velocity, , uniform acceleration?, ody is equal in equal intervals of time,, , celeration., antities: Initial velocity, fina], , When do you say that a body is oi, If the change in velocity of a moving b, then the body is said to have uniform ac, , Write the symbols of the following physical que, velocity, distance, acceleration, average velocity., Initial velocity =u, Final velocity = v, Distance ~ 5,, velocity = v_., , A body in motion has a velocity of -5 m/s. Is it speed or velocity?, The given quantity is velocity (as speed cannot be negative)., , Acceleration = a, Average, , A body thrown vertically upward rises up to a height of 10m, and comes, back to the initial position. Calculate, , (a) the total distance travelled by the body., , (b) displacement of the body., , (a) Total distance travelled by the body = 10 m+10m=20m, , (b) Displacement of the body = 0 [as the body comes back to the starting point], , SHORT ANSWER QUESTIONS : a, , State two characteristics of a moving body., , (i) A moving body requires a fixed reference point in;, motion. © point in its surrounding to describe, , (ii) A moving body changes its iti ,, : ) position co . —, with respect to its surrounding. ntinuously with passage of time, , Give differences between distance and displacement, , Placement is a vector quantity., , ver be —, Pf ZETO, it is always positive whereas, , displacement can be zero, positive or-negati, Ive., , Se a ee 7 ae de a, a, Se
Page 3 :
CQuide, , 3. The Speed of light is 3 x 10° my. What is the distance travelled by light in 1, hour:, , 3, , Sol: Here, speed of light = 3 x 198 m/s, time = 1 hour = 3600 seconds, , Distance =Speed « Time =3x 10° < 3600 m =10800x10* m =1.08x10 m, , ed of 36 km/h. It stopped in 10 seconds after, he acceleration of the car., , 4. Acar is moving with a spe, , applying brakes. Calculate ¢, Sol: Here,, , Initial velocity (u) =36 km/hr = SON TOOD me =10 m/s, 3600 s, , as the car comes to rest], , , , Now, acceleration (a ne a m/s?, , t 10 10, Hence, the acceleration of the car is -1m/s?, , , , (5. Give one example in which the velocity of a body is continuously changing., State whether its speed can remain constant?, , The motion of a satellite moving around the earth has uniform circular motion., Its speed remains constant., , Sol:, , , , 6. Plota v-t graph fora body moving under a, uniform acceleration. How will you find out, the distance from this graph?, , Sol:, , The distance travelled can be calculated from, the area under the graph., , , , 7. Name the type of motion of a body from the following distance-time graphs., , v y ¥ y, | ane —_ LY , a | pK., @ @ ii) iy, , { WON? LVL han A Ss
Page 4 :
Sol: (i) Rest. (ii) Non-uniform speed, , Sol: Given,, , Ofecondary cience Ix, , rmspeed (iv) Uniform speed, ity comes to rest in 62.5 m. If the, 2. find the initial velocity of the, , (iii) Unifo, tain initial veloc, rakes was 5 m/s, , A scooter moving ata cer, retardation dueto applied b, , scooter., , ‘on is negative acceleration], Acceleration (a) =—5 m/s? [as retardation 1s neg, , Final velocity (v) = 0 , [as the scooter comes to rest], Distance (s)= 62.5 m, From third equation of motion, we have, 2as =v —u", u> =v’ —2as, u* = 0° —2(—-5)(62.5), u’ =0+10x 62.5, u* = 625, u=~625 =25 m/s, , Hence, the initial velocity of the scooter is 25 m/s., , D. SHORT ANSWER QUESTIONS, , 1. A child walks from A to E along the sides ofaregular “2 tig, pentagon of side 10 m. Find the distance travelled by him §*, and the magnitude of his displacement., , Sol: Distance travelled by the child =AB+BC + CD, . 7 =, Displacement of the child = AE = 10 m. cee . a ©, , 10m 40m, , 2. Acar is moving with a velocity of 45 k, by the car in 1h; 1 minute and . 7 —* Calculate the distance travelled, , Sol: (i) Speed of the car = 45 km/h, , Distance travelled by the car in 1 hour = Sp eed _ 45 km/h, Time lh, , (ii) Speed of the car = 45 km/p= 45 km 45 km, lh 60min~ 0.75 km/min, , = 45 km
Page 5 :
| Guide, , Sol:, , Sol:, , , , , , , , , , , , Speed 0.75 km/min _, Distance travelled by the car in 1 minute = io | ae 0.75 ab, 45km 45km, , i = =——- = = 0.0125 km/sec, (iii) Speed of the car = 45 km/h th 3600 sec, , Speed 0.0125 km/sec, Distance travelled by the car in 1 second = nae = 0.0125 km, , Time 1 sec, , Draw the displacement-time graphs for the following situations:, (a) When the body is stationary., (b) When the body is moving with a uniform, , velocity. Displacement -———_——, (c) When the body is moving with a variable t, velocity. |, , , , (a) Fora stationary body, the displacement time, , graph is a straight line parallel to the time axis. The, , slope ofthe line is zero that indicates the velocity, , of the body is zero. Ff, (b) Fora body moving with constant velocity, the ee sy, displacement time graph is a straight line inclined, at any angle from the time axis. |, , , , , Displacement:, , , , , , (c) Fora body moving with non-uniform velocity,, the displacement time graph is acurved line. |, , , , time —>, , Explain with one example that uniform circular motion is accelerated, motion., , A stone tied to a thread and then rotated ina circular path with uniform speed is an, example ofuniform circular motion., , During the motion,the stone changes direction continuously to keep it on the circular, , path. Since, change in direction js acceleration, it can be said that uniform circular, motion is accelerated motion.
