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Monday, 20 November 2017

MCQ'S ON FORCE, NEWTON LAWS OF MOTION , MATTER AROUND US- CBSE, ICSE, SSC



1. In the adjoining figure, the tension in the string connecting A and B is
A)    g                      B) g                  C) 8g/9                       D) 10g/9

2. Two masses of 1 kg and 5 kg are attached to the ends of a massless string passing over a pulley of negligible weight. The pulley itself is attached to a light spring balance as shown in the figure. The masses start moving during this interval, the reading of spring balance will be
A)    more than 6 kg 
B)     less than 6 kg
C)     equal to 6 kg  
D)    none of the above


3. A body of mass M hits normally a rigid wall with velocity V and bounces back with the same velocity. The magnitude of impulse experienced by the body is

A)    zero

B)     MV

C)     √2 MV

D)    2 MV

4. A force of 6N acts on a body at rest and having a mass 4 kg. During the time of application of force, the body attains a velocity of 30 m/s. The time for which the force acts on the body is:

A)    180 sec.
B)     20 sec.
C)     45 sec.
D)    24 sec

5. An object of mass 2 kg is sliding with a constant velocity of 4 m/ s on a frictionless horizontal table. The force required to keep the object moving with the same velocity is

A)    32N
B)     8N
C)     0
D)    2N

6. A bullet of mass 20gm is fired from a gun of mass 8kg with a velocity of 400 m/s, calculate the recoil velocity of gun
 
 
A)    1m/s
B)     -1m/s
C)     2m/s
D)    -2m/s

7. The action and reaction forces referred to in the third law

A)    Must act on the same object
B)     Must act on different objects
C)     May act on different objects

D)    Need not be equal in magnitude but act in the same direction

8. Formula to find the average velocity of a body is given by

A)    V= u+ at                                                                   B)  S= ut + ½ a t2 
C)  Sn ={u + a/2(2n-1)}                                                  D) Vav=(u + v)/2

9. Force required in accelerating a 2 kg mass at 5 m/s2 and a 4 kg mass at 2 m/s2

A)    Same in both the cases
B)     2kg mass at 5m/s2 is greater than 4 kg mass at 2 m/s2

C)     2kg mass at 5m/s2 is less than 4 kg mass at 2 m/s2
D)    Zero in both the cases

10.  Which of Newton's laws best explains why motorists should buckle-up?

A)    the first law         
B)     the second law    
C)     the third law        
D)    the law of gravitation

11.A net force F acts on a mass m and produces an acceleration a. What acceleration results if a net force 2F acts on mass 4m?

A)    a/2         
B)     8a          
C)     4a
D)    2a

12. Action-reaction forces are

A)    equal magnitude and point in the same direction.   
B)     equal magnitude but point in opposite directions.
C)     unequal magnitude, point in the same direction.     
D)    unequal magnitude, point in opposite directions

13. Which of the following has minimum spaces among the particles?

A)    Solids
B)     Liquids 

C)     Gases                                                                                        D) None of these
14. A change of state directly from solid to gas without changing into liquid state (or vice versa) is called

A)    Evaporation
B)     Sublimation
C)     Diffusion
D)    Condensation

15. Which of the following is the simplest form of matter –

A)    Element 
B)     mixture 
C)     compound 
D)    none of these

16. The rate of evaporation decreases with

A)    increase in humidity 
B)     increase of temperature
C)     increase in wind speed
D)    increase of surface area

17. On converting 25°C, 38°C and 66°C to kelvin scale, the correct sequence of temperature will be

A)    298 K, 311 K and 339 K
B)     298 K, 300 K and 338 K 
C)     273 K, 278 K and 543 K
D)    298 K, 310 K and 338 K

18. Area under velocity-time graph tells us the

A)    time 
B)     acceleration
C)     displacement  
D)    velocity

19. Time taken by a train to slow down from 80 kmh-1 to 20 kmh-1 with a uniform deceleration of 2 ms-2 is

A)    9 s 
B)     10 s 
C)     8.3 s
D)    8.4 s

20. The distance (s) in metres travelled by a particle is related to time (t) in seconds by the equation of motion S = 10t + 4t2. What is the initial velocity of the body?

A)    10 m/s
B)     6 m/s
C)     4 m/s
D)    10 m/s2

21. When the distance that an object travels is directly proportional to the length of time it is said to travel with

A)    zero velocity
B)    constant speed
C)    constant acceleration 
D)   uniform velocity

22. A person travels distance πR along the circumference of a circle of radius R. Displacement of the person is

A)    R
B)    2R 
C)    2Ï€R
D)    zero

23. A body moving along a straight line at 20 m/s undergoes an acceleration of 4 m/s2. After two seconds its speed will be

A)   -8 m/s 
B)    12 m/s 
C)    16 m/s
D)   28 m/s

24. Which one of the following terms is used to indicate the natural tendency of an object to remain at rest or in motion at a constant speed along a straight line?

A)    velocity
B)    acceleration
C)    inertia
D)    force

26. A 44-kg child steps onto a scale and the scale reads 430 N. What is the magnitude of the normal force acting on the child?

A)    44 N 
B)     430 N 
C)     860 N
D)    215 N 

27. You are standing in a moving bus, facing forward,and you suddenly fall forward. You can imply from this that the bus's

A)    velocity decreased.
B)     velocity increased.
C)     speed remained the same, but it's turning right
D)    speed remained the same, but it's turning left.

28. m/s2 is the SI unit of –

A)    distance 
B)     displacement
C)     velocity
D)    acceleration.

29. Dry ice means –

A)    solid SO2
B)     solid water
C)     solid CO2
D)    solid CO

30. A state of matter which has a definite shape and fixed volume –

A)    Solid
B)     liquid
C)     gas
D)    none of these.

31. The act, process or state of the change in place or position of a body with respect to time and relative to the observer is said to be ………………

A)    Rest
B)    Stationary
C)    Motion
D)    none of the above

32. Which type of motion of an object that moves in a straight line ?

A)    Rectilinear motion
B)     Periodic motion
C)     Circular motion
D)     none of the above

33. The physical quantities used in displacement both direction and magnitude are called as:

A)    Vectors
B)     Scalars
C)     S.I
D)    C.G.S

34. The velocity of a body at a given instant is called as

A)    instantaneous velocity
B)     uniform velocity
C)     non-uniform velocity
D)    none of the above

35. Mass of object is quantitative measure of its inertia stated law is newton's

A)    first law
B)     second law
C)     third law
D)    fourth law

36. When a bus suddenly takes a turn, the passengers are thrown outwards because of

A)    Inertia of motion
B)    Acceleration of motion
C)    Speed of motion 
D)    Both (b) and (c)
37. A diwali rocket is ejecting 0.05 kg of gases per second at a velocity of 400 m/sec. The accelerating force on the rocket is

A)     20 m/sec
B)     20 N
C)    22 m/sec
D)     1000 N

38. A rocket is ejecting 50g of gases per sec at a speed of 500m / s. The accelerating force on the rocket will be

A)    125N
B)     25 N
C)     5N 
D)     Zero


39. On Kelvin scale 0OC is equal to –

A)    273 K
B)     -273 K
C)     0 K
D)    100 K
  

40. When we add sugar in water, particles of sugar disappear because they -

A)    are very small
B)     get into the spaces between water particles
C)     are moving
D)    all above

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