Answer:
Work done is 0.
Explanation:
Given that,
The circumference of an orbit for a toy on a string is 18 m, r = 18 m
Centripetal force, F = 12 N
In the circular path, the centripetal force is always perpendicular to the motion of the object. Thus it makes an angle of 90 degrees with the force and displacement. Hence, we can say that the centripetal force does not do any work on the toy when it follows its orbit for one cycle.
Answer:
0.125 volts
Explanation:
The induced emf can be sufficient to stimulate neuronal activity.
One such device generates a magnetic field within the brain that rises from zero to 1.5 T in 120 ms.
We need to find the induced emf within a circle of tissue of radius 1.6 mm and that is perpendicular to the direction of the field. The formula for the induced emf is given by :

Where
is magnetic flux
So,

So, the induced emf is equal to 0.125 volts.
Here we will say that there is no external torque on the system so we will have

here we know that

where we know that

Also we know that

initial angular speed will be

now from above equation



now we have

so final speed will be 2.41 rad/s
The correct answer is A. Each object in the universe that has mass attracts every other object that has mass.
Explanation:
The gravitational law proposed by Newton explains how the gravitational force works. The basic idea or premise in this law is that the gravitational law exists in all the universe, and occurs with all objects that have a mass. This includes the fact all objects or particles that have a mass attract all other objects with mass but this is also influenced by the distance between the objects, and the masses of each object. In this way, the gravitational force is equal to the gravitational constant multiplied by the mass of the two objects and divided by the distance between the objects.