Question

Block A is pushed across a horizontal surface at a constant speed by a hand that exerts force towards the right. Assume that there is friction between the block and the surface.

a. Draw an interaction diagram for the situation.

b. Use your interaction diagram to draw two free-body diagrams, one for the hand and the other for the block.

c. Rank in order from largest to smallest, the magnitudes of all of the horizontal forces you showed in part b.

d. Repeat this process (a-c) with a second Block B being placed in front of Block A. Assume the mass of Block B is more massive than A.

Answer 1

b. Rank in order, from largest to smallest, the magnitudes of all of the horizontal forces you showed in part a. For example, if Fcon D is the largest of three forces while equal, you can record this as FconDD on CFD on B Order: Explanation: FD on and FnE are smaller but THnN-fawh due to Newton's Third Law.These are an lbecouuse. Hne. S» olock is movina ot constant Speed.Because these are the onlitwo Forces on the lolock (Chorizontallythey must be eqyual ond opposite so that FnetO c. Repeat both part a and part b for the case that the block is speeding up BlockA tond H SonA Kon A The foree of thehondon blockAisequol ond oppesteto the Force ofLlock A onthe hand due to Newtonshird Low. They re -reoction pair. FuonA is laaer tran the force f friction becuse the block. İs Speeding up,Tt must hav anetForce in the direcion of ts tccelefoion on acmon

A second block B is placed in front of Block A of question 8. B is more massive than A: mB > mA. The blocks are speeding up Consider a frictionless surface. Draw separate free-body diagrams for A, B, and the hand. Show only the horizontal forces. Label forces in the form Fc reaction pairs. Hand onD. Use dashed lines to connect action/ Hand H BlockA Blocke Or AonH BonA'HonA b. By applying the second law to each block and the third law to each action/reaction pair, rank in order all of the horizontal forces, from largest to smallest. Order: F>F Explanation: The only horizontol Force onBis by Block A.In orcler for Block A to be also speedingup te reforce on it must be towards B. ThuS, FyonA MuS BonA by Newton's second low be areater than