The friction force between the object with a mass of 1kg and the horizontal plane is 5N. Under the action of 10N horizontal force, the object starts to move forward from static state, When the external force is removed after 2 m forward, the object continues to move forward for 1 m. at this time, what is the speed of the object? The object finally stops moving, and its total displacement is?

The friction force between the object with a mass of 1kg and the horizontal plane is 5N. Under the action of 10N horizontal force, the object starts to move forward from static state, When the external force is removed after 2 m forward, the object continues to move forward for 1 m. at this time, what is the speed of the object? The object finally stops moving, and its total displacement is?

The motion of an object is divided into two parts, uniform acceleration and uniform deceleration. The acceleration A1 of uniform acceleration is (10-5) / 1 = 5m / S ^ 2, the acceleration A2 of uniform deceleration is - 5m / S ^ 2, the velocity at rest before starting motion is V0 = 0m / s, the velocity when removing external force is V1, the velocity when stopping motion is V2 = 0m / s, the displacement of uniform acceleration is S1, and the displacement of uniform deceleration is S2
V1 ^ 2-v0 ^ 2 = 2a1s1, that is, V1 ^ 2 = 20
V2 ^ 2-v1 ^ 2 = 2a2s2, that is - V1 ^ 2 = - 10s2
So S2 = 2m
So the total displacement S = S1 + S2 = 4m