Thursday, May 17, 2012

IX SCIENCE ASSIGNMENT: MOTION


1.           [1] What  kind  of motion of a body  is represented by the graphs given  below  ?                           










2.           [3] (a)     Write  differences between speed and  velocity.                                                                      
(b)     The speed of a moving object  is x m/s .   Its velocity  is y m/s   What  is the similarity observed ?
3.           [2] (a)     Define  uniform circular motion.                                                                                     
(b)     Is the  uniform circular motion an  accelerated motion ? Give  reasons for  your answer.
4.           [5] The V-T graph of cars  A and  B which  start  from  the  same  place  and  move  along  a straight road  in the  same  direction, is shown. Calculate
 (i) the  acceleration of car A between 0 and  8s.
(ii) the acceleration of car B between 2s and  4s.
(iii) the points of time at which  both  the cars have  the same  velocity 
(iv) which  of the two  cars is ahead after8 sec. and  by how  much  ?
  















5.           [3] The velocity time graph of a ball of mass 20g moving along a stright line on a long table is given  in fig. How much  force does the table exert on the ball to bring  it to rest.













6.           [1] What  can  you  say  about  the  motion of a body  whose distance-time graph is a line parallel to time-axis.
7.        [3] A car starts  with  velocity  10 m/s and  accelerates at rate 5 m/s2 .  Find the final velocity when the  car has  travelled a distance 30 m.
8.           [2] A body  covers  a semicircle  of radius 7 cm in 5 second.  Find  its velocity.                                  
9.       [3] Draw  a graph velocity  versus time  for a body  starts  to move  with  velocity  ‘u’ under a  constant acceleration a for time  t.  Using  this  graph derive an expression for distance covered ‘s’ in time ‘t’.
10.        [1] State the type  of motion represented by the given  graph.    











11.        [2] (a)     Define  acceleration.                                                                                                            
(b)     A stone  describes a circular path  with  a constant speed.  State the  type of motion of the stone.
12.        [2]Write  any  two  equations of motion for a body  having uniform acceleration.                      
13.        [3] (a)   Differentiate between distance and  displacement.                                                        
 (b)   Under what  conditions is the magnitude of average velocity  of an object equal  to its average speed ?
14.        [1] “The  direction in which  an  object  moves  is given  by the  direction of velocity  of the object and not by the direction of acceleration”. Give an example to justify this statement.
15.    [3]The driver of a train A travelling at a speed of 54 km/h applies brakes and retards the train uniformly.  The train stops  in 5s.  Another train  B is travelling on the parallel track with  a speed of 36 km/h. This driver also applies the brakes  and the train retards uniformly. The train  B stops  in l0 s. Plot speed - time graph for both  the trains  on the same  paper.  Also calculate the distance travelled by each train after the brakes  were  applied.
16.        [2]Four  speed  - time  graphs are shown below. Which  graph represents the  following case ?
(a)     A ball thrown vertically upwards and  returning to the hand of the thrower ?
(b)     A body  decelerating to a constant speed and  then  accelerating.











17.        [2]A girl moves  with  the speed  of 6 km/h for 2 h and  with  the speed  of 4 km/h for the next 3 h.  Find  the average speed  of the girl and  the total  distance moved.
18.        [2]Examine  the  data  given  below  for motion of two  different objects  A and  B carefully and  state  whether the motion of the objects is uniform or non  uniform.  Give reasons.
Time                           Distance travelled by          Distance travelled by
object A in m.                   object B in m.

9.30 a.m                                    10                              12
9.45 a.m                                    20                            19
10.00  a.m                                  30                           23
10.15 a.m                                  40                            35
10.30  a.m                                 50                            37
10.45  a.m                                  60                           41
11.00 a.m                                   70                           44


19.        [2]Draw  velocity  time  graph for :                                                                                                           
(a)     An object moving with  uniform velocity.
(b)     An object moving with  non  uniform retardation.
20.        [3] The motion of a body  of mass  5 kg is shown in the v-t  graph. Find  from  graph.
(a)   its acceleration
(b)   the force acting  on the body
(c)   the change in momentum of in 2 seconds after  start
21.        [3] State three  equations of motion. Which of them  describes :                                                      
 (i)    velocity  - time relation
 (ii)   position -time  relation ?
22.        [3]Ali 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  30 km/h.  What  is the average speed for Ali’s trip  ?
23.        [2]What  is uniform circular motion ? Why  is it considered accelerated ?                                     
24.        [2] Which  of the  following is true  for  displacement ?   Justify your  answer for  the  true statement.                                                                                                                                 (a)     It can be zero.
(b)     Its magnitude is greater than  the distance travelled by the object.
25.        [1]Velocity time graph for a moving body  is shown in the diagram.  What  conclusion can be drawn about  the type  of motion ?

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