Which is heavier , a kilogram of lead or a kilogram of a polystyrene beads ?​

Aparticle with mass 1.81×10−3 kg and a charge of 1.22×10−8 c has, at a given instant, a velocity v⃗ =(3.00×104m/s)j^. what are the magnitude and direction of the particle’s acceleration produced by a uniform magnetic field b⃗ =(1.63t)i^+(0.980t)j^?

Aturntable that spins at a constant 74.0 rpm takes 3.10 s to reach this angular speed after it is turned on. find its angular acceleration (in rad/s2), assuming it to be constant, and the number of degrees it turns through while speeding up.

Which of the following forces require physical contact? tension air resistance friction magnetic force applied force