A car's engine provides a driving force of 30N. The car travels at a steady speed of 20m/s. What is the size of the resistive force acting against the driving force?

30 N

Explanation:

Since the car travels at a steady speed of 20m/s and has a driving force of 30N, there is no net acceleration and thus, the resistive force is also 30 N in magnitude but in the opposite direction to the driving force. This is shown below.

F - f = f' where F = driving force = 30 N. f = resistive force and f'= net force.

f' = 0 since there is no acceleration. So,

F - f = 0

F = f = 30 N

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.