Using g = 9.8 m/s2, the statement that best describes the roller coaster car when it is at the top of the loop-de-loop is that The car has both potential and kinetic energy, and it is moving at 24.6 m/s.
The correct answer is <span>B) The car has both potential and kinetic energy, and it is moving at 24.6 m/s.</span>
Answer: 
Explanation:
Given
Diameter of the rod 
length of rod is 
Resistivity of silicon is 
cross-section of the rod 
Resistance of rod is R
Current is given by
Answer:
Explanation:
a ) Momentum of first cart = mass x velocity
= 3 x 4.6 =+13.8 kg m /s
Momentum of second cart = 1.3 x - 1.9 = - 2.47 kg m /s
Total momentum = 13.8 - 2.47
= +11.33 kg m /s
b )
Let the velocity of first cart be v at the moment when second cart was at rest
total momentum = 3 x v + 0 = 3 v
Applying conservation of momentum law
3 v = +11.33
v = +3.77 m /s
(a). If the temperature of a substance is increased the density of it will also increased. The temperature is directly proportional to the density because the molecular activity of the substance will be affected by the temperature
(b).The mass of the substance doesn't at all. Because the amount of matter inside the substance cannot be affected by the temperature except that its water
