Forces and Newton's Laws

coefficient of friction

The ________: Number that tells how sticky two surfaces are.

Kinetic friction

________ must always act in the opposite direction of motion.

Normal force

________- perpendicular to incline.

Normal force

________: the force of a surface on an object that acts perpendicular to the surface.

Force of friction

the force of a surface on an object

Kinetic friction

friction force when something is moving along the surface and acts opposite the direction of motion

Static friction

friction force between two surfaces that arent moving relative to one another

Newtons third law

The force of Object A on Object B is equal in amount and opposite in direction to the force of Object B on Object A

Newtons second law

an objects acceleration is the net force it experiences divided by its mass, and is in the direction of the net force

A 2-kg block and a 5-kg block are connected as shown above. The coefficient of friction between the 5-kg block and the flat surface is μ = 0.2.

(a) Calculate the magnitude of the acceleration of the 5-kg block. (b) Calculate the tension in the rope connecting the two blocks.

(a)acceleration is 1.4 m/s2

(b) tension is 17 N

A 2.0-kg cart is given a shove up a long, smooth 30° incline. If the cart is traveling 8.0 m/s after the shove, how much time elapses until the cart returns to its initial position?

(A) 1.6 s

(B) 3.2 s

(C) 4.0 s

(D) 6.0 s

(E) 8.0 s

B