Answer:
C
Explanation:
When a substance is changing state, the heat supplied does not result in a rise in temperature. This is why, the heat supplied during change of state is referred to as 'latent heat'.
Latent heat is a heat that causes a change of state without a corresponding rise in temperature. During this time, the intermolecular bonds in the substance are broken.
Change of state will occur as regions in which there is no change in temperature with time such as point D on the graph.
A car speeding down a 20 foot hill
Answer:
Beta minus decay
Explanation:
Beta decay is due to a weak nuclear interaction, it takes place in the atomic nucleus and occurs when a neutron is converted to a proton, or a proton into a neutron. When a neutron is converted to a proton an electron and an electronic antineutrino are emitted from the nucleus, this is called beta minus decay.
Answer:
68.2 Quadrillion meters
Explanation:
A lightyear is the distance that light travels in one year.
Speed of light is 
So light covers 300,000,000 meters in one second.
One year has 31536000 seconds so , light covers

so 7.2 light years is

so 7.2 light years is
6.82 x 10^(16) meters or
68.2 Quadrillion meters
Force of gravity on an object is the weight of the object and is given by mass times accerelation due to gravity. The accerelation due to gravity is the accerelation of an object in free fall and is given by 9.8m/s^2. Given that the force of gravity acting on a child's mass on earth is 490 newtns, i.e. F = mg which means that 490 newtons = 9.8 times mass. Therefore, mass of the child is 490 / 9.8 = 50 kg.