Answer:
C
Explanation:
Q=mcΔθ
Q=quantity of heat , m= mass of the storage rock
Δθ= temperature change.
m= Q/(cΔθ)
Q=5.4
Δθ=62°C-20°C
=42°C
c=0.21cal/g.°C
m≈6100000g
m≈6100kg
<span>Based
on Newton's law of universal gravitation, the equation for the
gravitational force exerted by an object on another object is given by:
F = Gm1m2/(r^2)
where G is the universal gravitational constant, F is the gravitational
force exerted, m1 is the mass of the first object, m2 is the mass of the
second object, and r is the separation distance between the two
objects.
If the mass of both objects were doubled, then we would have: m1' * m2' =
(2m1) * (2m2) = 4m1m2. Assuming r stays constant (G is a constant so
that won't change anyway), then this means that the new force will be 4
times greater, ie 8N * 4 = 32N of gravitational force. </span>
The speed of the ball is always zero and the acceleration is always -g when it reaches the top of its motion. This is because when the ball is free, only gravity acts on it which is always downwards, hence g is the net acceleration and it is always negative. However the velocity does not direction change instantly, negative acceleration first slows down the ball with a positive velocity, until that point the ball keeps moving up, then the ball velocity becomes zero just before changing direction and becoming negative after which the ball will now go down along gravity. Hence the ball velocity is zero at the top (neither going up nor down). Mathematically this can be seen as velocity is the integration of acceleration.
Explanation:
A positive point charge Q is fixed on a very large horizontal friction less tabletop. A second positive point charge q is released from rest near the stationary charge and is free to move.
As per the law of conservation of energy the change in kinetic energy is equal to the change in potential energy.
The mathematical expression for the conservation of energy is given by :
On solving the above equation, we get the value of v as :
In the above expression, as the term 
increase, as 
increases, the value of 
decreases. So, the correct option is (B) "As it moves farther and farther from Q, its speed will increase".
