Answer:
The light wave could be reflected by the object
The energy required to heat a substance is related by the formula:
Q = mCpΔT ; where Q is the energy, m is the mass of the substance, Cp is the specific heat capacity and ΔT is the change in temperature.
2000 = (4)(Cp)(5)
Cp = 100 Joules / g °C
The speed of sound is greater in ice (4000 m/s), then in water (1500 m/s), then in air (340 m/s). The explanation for this is the differente state of the matter in the three cases.
In fact, sound waves travel faster in solids (like ice), then in liquids (like water), then in gases (like air). This is because the speed of the sound wave depends on the density of the medium: the greater the density, the faster the sound wave. This can be easily understood by thinking at how a sound wave propagates: a sound wave is a vibration of molecules, which is transmitted throughout the medium by collision of the molecules. Therefore, the smaller the spacing between the molecules (such as in solids), the more efficient is the propagation, and so the sound wave is faster. On the contrary, there is a large spacing between molecules in gases (such as in the air), so there are less collisions between the molecules and so the wave is not transmitted efficiently, and so it has less velocity.
Answer:
Explanation:
Given
mass of bus along with travelers travelling in North direction is 
speed of bus towards North 
mass of bus travelling in South direction is 
speed of bus 
mass of each Passenger in south moving bus 
Momentum of North moving bus
Momentum with south moving bus
For total momentum to be towards south
should be greater than 0
thus for least value of n
