1. 25
2. 55-25 = 30
Hope this helps! :)
There are different types of contact forces like normal Force, spring force, applied force and tension force.
Weather
Particles in air such as smoke smog
Potential Energy (P.E) = Mass x
Acceleration due to Gravity x Altitude. Putting this value in the above equation we get, Dimensional Formula of
Potential energy= M1L2T-2.