<span>The platform scale consists of a combination of third and first class levers so that the load on one lever becomes the effort that moves the next lever.Through this arrangement, a small weight can balance a massive object. If x=450 mm,determine the required mass of the counterweight S required to balance a 90-kg load, l.</span>
Answer:

Explanation:
If the collision is elastic and exactly head-on, then we can use the law of momentum conservation for the motion of the 2 balls
Before the collision

After the collision

So using the law of momentum conservation


We can solve for the speed of ball 1 post collision in terms of others:

Their kinetic energy is also conserved before and after collision


From here we can plug in 






HCl + NaOH -> H2O + NaCl
CaCO3 + KI -> K2CO2 + CaI2
AlF3 + Mg(NO3)2 -> Al(NO3)3 + MgF2
Answer:
see the attachment
Explanation:
take coordinate system correctly. use formulas of projectile motion
Wooden spoons don't quickly heat to hot temperatures not nearly as fast as metal does. Metal conducts heat faster than wood — if the head of the spoon is in a hot liquid, the handle will get hot faster if it's made out of a metal.