A biker pedals hard for 3 seconds. What is his initial velocity if he accelerated by 4m/s2 until he's going 20m/s. (Which equation should I use?)

The mass of the sun is 1.99×1030kg and its distance to the earth is 1.50×1011m. what is the gravitational force of the sun on the earth?

Ahanging spring stretches by 35.0 cm when an object of mass 450 g is hung on it at rest. in this situation, we define its position as x = 0. the object is pulled down an additional 18.0 cm and released from rest to oscillate without friction. what is its position x at a moment 84.4 s later? express your answer in cm.

Atoaster oven has a resistive heating element. the average rate at which it dissipates energy as thermal energy is 1.00 \(\rm kw\). in the united states, emf amplitude in household circuits is \(\mathcal e_{\max}\) = 170 \({\rm \; v}\) and the \(\rm ac\) oscillation rate is 60 \(\rm hz\). part a what is the root-mean-square current through the heating element?