Physics Test 11...

Minimum speed of a plane on runway for take off was found to depend on area of blade of wings, density of material of plane and acceleration due to gravity. If take-off speed of a model toy plane is 10 m/s then take-off speed of a real plane identical in all aspects but scaled up 10³ times, will be

A particle travels with speed 10 m/s for 2 sec towards east, then turns left and moves for 1.5sec with same speed. What is magnitude of displacement? 

The projection of a vector  on the y–z plane has magnitude :-

In a new system of units, unit of mass is taken as 50 kg, unit of length is taken as 100 m and unit of time is 1 minute. What will be weight of a body in this system, if in S.I. system, its weight is 10N ?

A charged ball of charge +q₁ is revolving around another charge +q as shown in a conical pendulum. The motion is in a horizontal plane :-

In the given figure radius of the conducting sphere is increasing according to the relation R = Vt. A point charge q is fixed at distance ‘a’ from centre of conducting sphere. The current flowing in the earthen conductor at the instant when R < a is 

A nonconducting ring of radius R carries no NET charge. Then :- 

Which of the following sets of physical quantities cannot be taken as fundamental physical quantities?

We know that if charge is distributed on a body, these charges interact to give a certain self energy to the body. This self energy can be calculated in many ways. One of the ways is to integrate the energy spread out in entire space in form of electric field. 

We can assume an electron to be like a uniformly charged thin shell of radius r₀ having self energy E₀. This energy has been estimated in nuclear reactions as 0.51 MeV. From this we can find out an approximate radius of the electron.

What is the approximate radius of electron ?