3. A toy car is moving on a track at 4.0 m/s. If the toy car has 16 J of kinetic energy, what is the mass
of the car in kilograms?

m = 2 kg

Explanation: The kinetic energy of the toy car is expressed in

KE = 1/2mv².

To find the mass, we will derive the formula: m= 2KE/ v²

m = 2 ( 16 J) / (4m/s)²

= 2 kg

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.