Physistri

Here on Earth we see exactly the same features of the moon’s surface because the moon spins once around its axis.It spins in the same amount of time it needs to orbit the Earth,which is about 27.32 days. 

As we know that in newtonian (Newtonian) physics, gravity is a force between two objects with mass. F=Gm1m2/r2, if m1 is your mass,m2 is the mass of earth or moon and r is the radius (distance between forces ) of the earth or moon or other planet. When the ratio m2/r2 increases the force of gravity increases.Now, if we take mass of Earth m2E=5.97*1024 kg and its radius is rE=6378 km…. after calculation FE=9.8m2 N .For moon, m2M=7.34*1022 kg and rM=1737.4 km and after calculation F=1.62m2 N .The pull of gravity on you on earth is greater than on moon a nutshell less gravity is due to less mass. According to Einstein gravity is the curvature of space-time created by massive objects.Greater the mass is greater the curvature more the pull.

Why do some metals go rusty ?  Iron and steel rust when they come in contact with water and oxygen.When water hits iron for example it reacts with carbon dioxide (CO2) in air to form carbonic acid, then iron is dissolved.Some of water will break into its component oxygen and hydrogen.This oxygen reacts with dissolved iron to from iron oxide . Iron oxide is rust. 

Like we said in the previous question that every year is divisible by 4 is a leap year.But 1700 , 1800 and 1900 are divisible by 4 and not leap years. because of the earth needs exactly 365.242199 days not 365.25 to  orbit the sun.So,a year is a leap year if it is not only divisible by 4 but also by 400. 

Why do we have a leap year ?  A year is the time it takes Earth to orbit the sun.The calendar is divided into 365 days .It takes for the Earth to orbit the sun not exactly 365 days but about 365.25  days. So,every four years we throw in an extra day. 

What makes ice slippery is the water layer on its surface.The cause of this water layer is the pressure applied by the skate,the pressure increases the melting point of ice causing the outermost layer to melt.And  after the skate would slide across,a sheet of water would refreeze again as soon as the skate passed.Another scientists claim that the reason is friction between the skate and the ice.The friction generates heat that melts outer layer of ice.