Which part of the atom determines the chemical properties and chemical reactivity of an element? A. The number of valence electrons
B. The total number of electrons
C. The number of neutrons
D. The number of protons

Why is there friction between objects

The position of a dragonfly that is flying parallel to the ground is given as a function of time by r⃗ =[2.90m+(0.0900m/s2)t2]i^− (0.0150m/s3)t3j^. a: at what value of t does the velocity vector of the insect make an angle of 34.0 degree clockwise from the x-axis? b: at the time calculated in part (a), what is the magnitude of the acceleration vector of the insect? c : at the time calculated in part (a), what is the direction of the acceleration vector of the insect?

Why is metal often used for cooking pan?