Plz help Suppose one of the three students in Guided Example 7.6 stops pushing the car after 6.00 s. In this case the force exerted on the car is 305 N for the first 6.00 s and 215 N for the second 6.00 s.
(a) What is the final momentum of the car?
(b) What is the final speed of the car?

Aspring with an unstrained length of 0.071 m and a spring constant of 2.6 n/m hangs vertically downward from the ceiling. a uniform electric field directed vertically upward fills the region containing the spring. a sphere with a mass of 5.29 10-3 kg and a net charge of +7.2 µc is attached to the lower end of the spring. the spring is released slowly, until it reaches equilibrium. the equilibrium length of the spring is 0.058 m. what is the magnitude of the external electric field?