15 questions
_______ rotary electrical motors that converts direct current electrical energy into mechanical energy
AC Motor
DC Motor
KC Motor
All of the above
If Ma = mass of bottle, Mb = mass of first clip and Mc = mass of second clip, then
Surely Ma = Mb
Surely Ma = Mb + Mc
It is possible to have Ma > Mb + Mc
It is possible to have Ma < Mb + Mc
Find the correct statements.
Homopolar motor produces constant circular motion?
i. because the polarities of the magnetic fields do not change.
ii. because the polarities of the magnetic fields keep changing
iii. the direction of the force will not change and the wire will rotate in a constant circular motion.
i and ii
i and iii
iii and ii
none of the above
If a particle moves with constant angular velocity in a circle then during the motion its
Momentum is conserved
Energy is conserved
Both energy and momentum is conserved
None of the above is conserved
Talcum powder was displaced because
The density of the powder is smaller then the density of the soap solution.
The density of the soap solution is smaller than the density of the powder
The surface tension of the soap solution is smaller than that of water
The evaporation of the soap solution is faster than that of water
A tachometer is a device to measure
Gravitational pull
Speed of rotation
Surface tension
Tension in spring
the possible acceleration-time graph of the object during the motion of the ball are/is
None
The possible graph(s) for the vertical component of velocity and time in the situation of the previous question is (are)
In the same situation, the possible graph(s) for the variation of position in vertical direction with time is/are
None
The path of the laser beam becomes visible when the powder was sprinkled. This is because
Light started travelling in all the directions.
Dispersion of light
Chalk dust was red in colour
red light has longest wavelength
Case 1 = Bottle is completely filled.
Case 2 = Bottle is completely empty.
Case 3 = Bottle is partially filled.
Mark the correct statement(s)
It is most difficult to spin the bottle in case 3.
We can apply only small forces on the bottle in case 3, as compared to the other cases.
Energy given to the bottle by the hand is reduced due to collisions of parts of the water in case 3
The moment of inertia about the spin axis is the largest in case 3.
Mark the correct statement(s)
By releasing the fingers the volume of the tube is increased.
By releasing the fingers the pressure in the tube is decreased.
The paste went back into the tube because the mouth of the tube attracts the paste.
The force by air on the paste is increased when it comes out.
Mark the correct statement(s)
The smoke comes out of the ash sticking to the stick.
The smoke comes out of the place where it is seen burning red.
The smoke comes out of the black material at some distance from point of burning.
When the stick is shook the flame gets extinct because cold air gets mixed with the flame.
When the stick is shook the flame gets extinct because up down motion doesn’t allow the flame to go up steadily.
Assume that the food rotates about its center of mass. The net force on food is
Zero
Along the direction of motion
Opposite to the direction of motion
At some angle to the direction of motion
The girl is holding the wooden stick (“DANDA”)
Because it increases the total weight which helps in balancing.
For entertainment only
Because it increases the moment of inertia which helps in balancing.
To ensure that the vertical line through the center of mass passes through the rope