What is the magnitude of a point charge that would create an electric field of 3.90 N/C at points 4.80 m away?

When a 5.0kg cart undergoes a 2.2m/s increase in speed, what is the impulse of the cart

If y gets smaller as x gets bigger and y have an relationship?

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.