Rubbing both pieces cause each piece to have a negative charge.
When two parts have the same they repel each other, so holding one piece up tot he end of the other piece would push it away.
Because one piece is held in the middle by a string, it would rotate the piece in a circle.
If they held the piece to the other end of the one held by a string it would start to rotate in the opposite direction.
Answer:
The solution and the explanation are in the Explanation section.
Explanation:
According to the diagram that is in the attached image, the EFFORT force at point A and the load is at O point. The torque due to weight is:
TA = W * (a * cosθ)
The torque due to effort at C point is:
TC = E * (b * cosθ)
The net torque is equal to 0, we have:
Tnet = 0
W * (a * cosθ) - E * (b * cosθ) = 0

From the figure, you can observe that a/b < 1, thus E < W
To calculate the specific heat capacity of an object or substance, we can use the formula
c = E / m△T
Where
c as the specific heat capacity,
E as the energy applied (assume no heat loss to surroundings),
m as mass and
△T as the energy change.
Now just substitute the numbers given into the equation.
c = 2000 / 2 x 5
c = 2000/ 10
c = 200
Therefore we can conclude that the specific heat capacity of the block is 200 Jkg^-1°C^-1
Answers:
a) 
b) 
Explanation:
a) The centripetal acceleration
of an object moving in a uniform circular motion is given by the following equation:
Where:
is the angular velocity of the ball
is the radius of the circular motion, which is equal to the length of the string
Then:
This is the centripetal acceleration of the ball
b) On the other hand, in this circular motion there is a force (centripetal force
) that is directed towards the center and is equal to the tension (
) in the string:

Where
is the mass of the ball
Hence:

This is the tension in the string