Continuation with Force and Friction!

For the last few days we have been doing experiments to learn about force and friction.
From these experiments we have learned:

·         Increasing the mass of the cart increases the friction and force.

·         The rougher the surface the greater the friction and force.

·         When an object is pulled up a slant there is a greater amount of force due to gravity pulling the object down.

·         When an object is pulled down a slant there is less force and friction because gravity is pulling the object down the slant.

·         Force acts through the centre of the object. Meaning that no matter what the surface area is there will be the same amount of friction.  

After talking as a class about our results with the experiments we did an example with force.

A 4.0 kg block of wood is sliding on a horizontal table top. What force must be applied to the mass to give it an acceleration of 0.50m/s²? The coefficient of kinetic friction is 0.30.

m= 4.0kg                F_net=ma                                                    F_n=mg
a= 0.50m/s²                              =(4.0kg)(0.50m/s²)                              = (4.0kg)(9.8m/s²)
μ_k= 0.30                        = 2.0N                                                    = 39.2N
F_a=?
F_net=?                                                                  F_f= μF_n                                                                 
F_f=?                                                                                                    = (0.30)(39.2N)                            
F_n=?                                                                        =11.76N 

                                               F_net= F_a + F_f
                           2.0N[forward]= F_a + (-11.76 [forward])

                                           F_a= 2.0N[forward] + 11.76N [forward]

                                             F_a= 14N [forward]

After the example we did questions from the text book on page 169, #1-4. Lastly, Mr. Banow also mentioned about a Friday quiz.

Kenzie is next!