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Author Topic: [Solutions] All Physics Answers To The Quiz  (Read 53732 times)

Offline Mr. Babatunde

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[Solutions] All Physics Answers To The Quiz
on: February 10, 2020, 01:28:03 AM


[Physics I] Introduction And Concepts Of Matter (Solutions)

1. Anything that has weight and occupy space is what?

A. Matter ✔
B. Motion
C. Mass
D. Physics

2. Matter exist in how many state ?

A. 4
B. 3 ✔
C. 2
D. 6

3. One of the Factors affecting Diffusion is what?

A. Density ✔
B. Motion
C. Velocity
D. Acceleration

4. The process by which different forms of matter (fluid) mix intimately with one another owing to the kinetic nature of their particles or molecules is what?

A. Density
B. Diffusion ✔
C. Brownian motion
D. Pressure

5. Has definite volume, but no definite shape is what?

A. Solid
B. Liquid ✔
C. Gas
D. All of the above

6. Has definite shape and volume is what?

A. Solid ✔
B. Liquid
C. Gas
D. Non of the above



7. The mass number of neutron is what?

A. 2
B. +2
C. -2
D. 1 ✔

8. The evidence that molecules exist in matter and that the molecules are continually in motion is what?

A. Atom
B. Brownian Motion ✔
C. Potential energy
D. Molecule



9. Forces which make molecules of different substance to attract, and it occurs on water in a glass cup is what?

A. Adhesive forces ✔
B. Cohesive forces
C. Motion force
D. Pressure

10. The movement of water molecules from a region of higher concentration to a region of lower concentration through a semi-permeable membrane is?

A. Water
B. Osmosis ✔
C. Osmoreguation
D. Diffusion



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Offline Mr. Babatunde

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[Physics 4] Speed, Velocity And Acceleration (Solutions)
Reply #1 on: March 09, 2020, 11:04:40 AM


[Physics 4] Speed, Velocity And Acceleration (Solutions)

1. A baseball is pitched at 40 m/s (90 mph) in a Major League game. The batter hits the ball on a line drive straight toward the pitcher at 50 m/s (112 mph). Determine the the acceleration of the ball if it was in contact with the bat for 1/30s

   solution

   Acceleration is the rate of change of velocity with time. Since velocity is a vector, this definition means acceleration is also a vector. When it comes to vectors, direction matters as much as size. In a simple one-dimensional problem like this one, directions are indicated by algebraic sign. Every quantity that points away from the batter will be positive. Every quantity that points toward him will be negative. Thus, the ball comes in at −40 m/s and goes out at +50 m/s. If we didn't pay attention to this detail, we wouldn't get the right answer.

   v0 =     −40 m/s
   v =     +50 m/s
   Δt =     1/30s
   a =     ?

   a =     v−v0/Δt = (+50 m/s) − (−40 m/s) / 1/30s
   a =     (+90 m/s)(30s−1) = +2700 m/s2
   a = 2700 m/s2

2. The diagram above represent the velocity time graph of a body in motion. The total distance traveled by the body is 195m. Calculate the acceleration of the body in section OP of the graph

   Solution

   U = O, S = 195m, t = 6sec
   V = U + at
   V = o + a6 = 6a m/s

   Distance traveled;
      S = (1/2 x 6 x V) + (5 x V) + 1/2 x 10 x V
      S = 3V + 5V + 5V
      S = 13V

      Therefore;

      195 = 13V
      AND Recall; V = 6a m/s

      13V = 13 x 6a
         = 78a

      a = 195/78
      a = 2.5m/s2

3. A particle is dropped from a vertical height h and falls freely for a time t.  With the aid of this sketch, h varies with



A. i and t
B. t and t2
C. h and t
D. h and t2

4. A particle is projected horizontally at 15ms-1 from a height of 20m.
Calculate the horizontal distance covered by the particle just before hitting the ground. [g = 10 ms-2]


Solutions

   Let R represent the horizontal distance covered at time, t.

     h   = ½gt2                                                                                           
       20  = ½ x 10 x t2                                                                                     
        t  = 2s                                                                                               
       R  = ut
       =  15 x 2 = 30m   

4.  A body at rest is given an initial uniform acceleration of 6.0 ms-2 for 20s after which the acceleration is reduced to 4.0 ms-2 for the next 10s. The body maintains the speed attained for 30s.
from the velocity-time graph of the motion given, calculate the average speed during the same time interval.


 

    Solutions

    Let V1  = maximum velocity after 20 sec.
       V2  = maximum velocity after 30 sec.

    (I)
    Then  V1 = 6x20
          V1  = 120 ms-1 
          Also  V2 – V1   =   4x10
             V2 – V1  = 40
             V2  =  120 + 40
             V2  =  160 ms-1
                        Maximum speed = V2 = 160ms-1
     (II)
        Total distance covered = Area of Δ + Area of trapezium after 1st  30 seconds
         =  ( ½  x 20 x 120)  + ½ (120 + 160) x 10
          =            1200  + 1400
           =          2600m   

    (III)
        Average speed  =   Total distance / Total time
                    = 2600/30
                    = 86.67 ms-1

5. For the velocity time graph shown in the figure, the distance covered by the body in the last two seconds of its motion is what fraction of the total distance travelled by it in all the seven seconds?



Solutions

   Distance covered is equal to the area under velocity-time graph.
   Distance in last two seconds s2 ​= 1/2 × 8 × 2 = 8m
   Total distance = 1/2 × 8 × (6+2) = 32m
   Fraction of the distance covered by the body in the last two seconds of its motion to total distance traveled by it in all the seven seconds is 8/32 = 1:4 or 1/4

6. A ticker-timer uses 1/5s to 8cm length of a ten tick. What is the velocity?

   Solutions

      Velocity = Displacement/time
       = 8 ÷ 1/5
       = 40cm/s

7. The SI unit of speed and velocity is

A. m/s ✔
B. m/s2
C. m
D. s/t

8. Speed can be define as ______

A.  the rate of change of time only
B.  the rate of change of distance with time ✔
C.  the rate of change of distance only
D.  the rate of change of velocity with time

9. Acceleration can be define as ________

A. the rate of change of velocity with time ✔
B. the rate of change of distance with time
C. the rate of change of time alone
D. Non of the above

10. The SI unit of acceleration is

A. m/s
B. m/s2 ✔
C. m
D. s/t




Offline Mr. Babatunde

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[Physics 5] Waves , Types Of Waves And Properties Of Waves (Solutions)

1. A transverse wave travels a distance of 80cm in 10s. If the distance between successive trough of the wave is 4cm, Calculate the frequency of the wave.

   Solution;
      λ = 4cm , D = 80cm , t = 10s , f = ?

      v = fλ

      D/t = fλ

      80/10 = f x 4

      8 = 4f

      f = 8/4

      f = 2Hz

2. The distance between identical points in the adjacent cycles or crests of a wave is called ?

A. Frequency
B. Wavelength ✔
C. Amplitude
D. Phase

3. _______ is a disturbance in a medium that carries energy without a net movement of particles.

A. Transverse waves
B. Waves ✔
C. Electromagnetic waves
D. Water waves

4. ______ is a wave which needs a medium in order to propagate itself

A. Mechanical waves ✔
B. Water waves
C. Sound waves
D. Longitudinal waves

5.  If the particles of the medium are vibrating to and fro in the same direction of energy transport, then the wave is a ______ wave.

A. Longitudinal ✔
B. Sound
C. Standing
D. Transverse

6. If the energy in a longitudinal wave travels from south to north, the particles of the medium would be vibrating _____.

A. From north to south, only
B. Both north and south ✔
C. From east to west, only
D. Both east and west

7. A periodic and repeating disturbance in a lake creates waves which emanate outward from its source to produce circular wave patterns. If the frequency of the source is 2.00Hz and the wave speed is 5.00m/s then the distance between adjacent wave crests is.

Let λ=wavelength; then v = λf. In this problem, it is given that v=5.00 m/s and f = 2.00 Hz.
 λ = v / f = 2.50 m.

A. 0.200
B. 0.400
C. 1.25
D. 2.50 ✔

8. What is the frequency of a wave that has a speed of 0.4 m/s and a wavelength of 0.020 meter?

Let λ=wavelength; then v = λf. In this problem, it is given that v=5 m/s and λ = .02 m.
yields f=v/λ =20Hz.

A. 10Hz
B. 20Hz ✔
C. 0.008Hz
D. 0.5Hz

9. A period of 0.005 seconds would be equivalent to a frequency of ____ Hz

The period and the frequency are related by a reciprocal relationship; that is, f = 1/T.

A. 20
B. 50
C. 200 ✔
D. 500

10. When a pulse reaches a boundary between two different media, it will be____.

A. reflected, only
B. transmitted, only
C. partly reflected and partly transmitted ✔
D. neither reflected nor transmitted







 


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