Solutions of physics online class test 4 of class 7.

 1.Which is not an example of an oscillatory motion

Ans.Earth's Revolution around the sun.

2.Which is is not an example of of vibratory motion

Ans.Motion of a charkha

3.which is Not an example of periodic motion

Ans.None of these.

4.Which among the following is odd one

Ans.Moon's Revolution around the earth

5.Pick the odd one among the following

Ans.A carpenter's saw

6.Which is not an example of a circular motion

Ans.None of these.

7.A boy goes from his house to school by bus at a speed of 40 kilometre per hour and returns back through the same route at a speed of 30 kilometre per hour. The average speed of his journey is

Ans. Take the LCM of 40  and 30 = 120

Take it as distance =120 km

T₁=120km/40 kmh-¹

    = 3h

T₂= 120km/30kmh-¹

     = 4h

Average speed=total distance travelled/total time taken

    = (120km + 120km)/(3h+4h)

    = 240 km/ 7h

  = 34.285 kmh-¹

8.Which statement is false

Ans.Mass always acts vertically downwards.

9.Weight of a body is 600N on the surface of moon. What would be the weight of the body on the earth surface?

Ans.3600N

10.A car moves a distance of 30 km in 2 hours. what is the speed of the car in S.I. unit?

Ans. Speed=distance/time

                    = 30km/ 2h

                    =15 kmh-¹

                    = 15× 1kmh-¹

                    = 15×5/18 ms-¹

                    = 75/18 ms-1

                    =4.16666 ms-¹

                     ≈4.17 ms-¹

11.A bus is running at a constant speed of 60 km per hour. What will be the distance covered by the bus in 20 minutes?

Ans. Speed=60km/h

Time=20 minutes

        =20×1 minute

       = 20× 1/60 h

       =1/3 h

Distance=?

Speed=distance/time.

Speed×time= distance

Distance= speed×time

                = 60 kmh-¹ × 1/3 h

                = 20 km.

12.Rajdhani express leaves New Delhi at 4:30 p.m. and reaches Ranchi that is at a distance of about 1000 kilometre at 3:30 a.m. the next day. Find its speed?

Ans. Time between 4:30 p.m. to 3:30 a.m.=11 h

Distance travelled= 1000km

Speed=?

Speed=distance/time.

          = 1000km/ 11h

          = 90.909090 kmh-¹

          ≈91 kmh-¹.

13.Find the time taken by a train moving at 80 kilometre per hour to cover 600 kilometre?

Ans. Speed=distance/time

Speed×time= distance

Time=distance/speed

         = 600 km /80kmh-¹

        = 60/8 h

        =60/8 × 60 minutes

      = 3600/8 minutes

     = 450 minutes.

14.The motion of the earth is

Ans.Periodic motion

15.The motion of a pendulum shows

Ans.Oscillatory motion

16.ms-¹ is used to measure

Ans.Speed

17.Nkg-¹ is the unit of

Ans.Acceleration due to gravity

18.The weight of a a boy is 60 Kgf. His mass will be

Ans.60kg

19.A ball falls down vertically. Its motion is

Ans.Translatory motion

20.If a body covers equal distances in in unequal interval of time, motion is said to be

Ans.Non- uniform motion