Homework 6

The following questions are based on chapter 4, section 2, section 4, and section 5 in our textbook.  (Each of those is a separate link!)  I also recommend looking at the section on problem solving strategies if you’re struggling (and even if you’re not!)

These questions are due at the end of class today!


Answer the following in complete sentences.  Draw a picture to aid you explanation, but a drawing alone is insufficient.

1) Describe a situation in which the net external force on a system is not zero, yet its speed remains constant.

2) A system can have a nonzero velocity while the net external force on it is zero. Describe such a situation.

3) A rock is thrown straight up. What is the net external force acting on the rock when it is at the top of its trajectory?

More Traditional math based problems. 

4) What net external force is exerted on a 1100-kg artillery shell fired from a battleship if the shell is accelerated at2.40×104 m/s2? What is the magnitude of the force exerted on the ship by the artillery shell?

5) A cleaner pushes a 4.50-kg laundry cart in such a way that the net external force on it is 60.0 N. Calculate the magnitude of its acceleration.

6) A brave but inadequate rugby player is being pushed backward by an opposing player who is exerting a force of 800 N on him. The mass of the losing player plus equipment is 90.0 kg, and he is accelerating at 1.20 m/s2 backward.

(a) What is the force of friction between the losing player’s feet and the grass?

(b) What force does the winning player exert on the ground to move forward if his mass plus equipment is 110 kg?

(c) Draw a sketch of the situation showing the system of interest used to solve each part. For this situation, draw a free-body diagram and write the net force equation.