A 30 gram ball rolls along a flat surface at a constant speed in the same direction over 4 meters in 20 seconds. Which is the speed of the ball? (speed = distance = time)
A. 0.2 meters per second
OB. 0.5 meters per second
c. 20 meters per second
D. 80 meters per second

Please answer this FAST!

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants

3. a lunar exploration vehicle was created by a research team. it weighs 3,000 kg on the earth. it needs an acceleration of 10 m/s2 on the moon. in order to have the same acceleration, what will be the net force acting on the vehicle on the earth?

By what factor does the drag force on a car increase as it goes from 65 to 110 km/h?