Momentum transfer of Light to Object Can light made of photons in theory topple  lets say a car?
I know basic photon energy is hv where v is frequency.
So according to conservation of linear momentum, if high enough and large amount of photon falls, would not it topple objects in particle nature of light.
 A: This depends on what the car is made of, but the likely answer is no.
For light, the relation $$E = pc $$ holds, so $$\frac{dE}{dt} = c\frac{dp}{dt} $$ $\frac{dE}{dt}$ is power, and $\frac{dp}{dt} $ is force, so for light $$F = \frac{P}{c} $$ for absorption, and $$F = \frac{2P}{c} $$ for reflection. 
So, how much force do you need to apply to a car to tip it over? As a complete SWAG, let's say 1000 kgF, or about 10,000 newtons. Plugging this in, we get $$P = Fc = 10^4\times 3\times10^8 = 3\times10^{12} = 3 \text{ TW}$$ And yes, the T stands for terawatts, as in 3 million million watts. To put it in perspective, the entire annual US electrical power production is 2 TW-hr. To put it another way, that's the equivalent of burning about 70,000 tons of oil per second, so the car is going to get pretty hot. I suspect such a light beam would either vaporize the car or punch a hole in it before it tipped over, although this would be a matter to address using rather more sophisticated analysis than I'm willing to do.
You could, of course, specify that the car is perfectly reflective, in which case it would only take one half the power. Make sure to wear your safety goggles.
