A student designs an experiment to determine how the type of surface affects the amount of force needed to roll a ball 20 meters. What tool would the scientist use to measure the mass of the ball?

Is a pencil falling to the floor anon contact force, a force, or a contact force

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added

The number of moles of a given mass of a substance can be found without knowing its molecular formula or molar mass. true false