The kinetic energy of an object can be determined using the equation , where is the kinetic energy, is the mass, and is the speed of the object. What is the mass of an object moving at a speed of 12 that has 36 J of kinetic energy?

0.5kg

Explanation:

Given parameters:

Speed of the object  = 12m/s

Kinetic energy  = 36J

Unknown:

Mass of the object  = ?

Solution:

Kinetic energy is the energy due to the motion of a body. It is mathematically expressed as;

     K.E = m v²  

 Insert the parameters and solve;

    36  =   x m x 12²

     36  = 72m

       m  = 0.5kg

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g

the answer would be a