Homework

1. Here are the densities and radii of planets in our solar system (in grams per cm³ and km, respectively)

Mercury         5.4 g cm^-3       2,440 km  
Venus            5.2 g cm^-3       6,052 km  
Earth             5.5 g cm^-3       6,378 km  
Mars              3.9 g cm^-3       3,396 km  
Jupiter           1.3 g cm^-3       71,492 km  
Saturn           0.7 g cm^-3       60,268 km  
Uranus          1.3 g cm^-3       25,559 km  
Neptune        1.6 g cm^-3       24,764 km

How much would you weigh on these different planets? 1 pound is equal to 0.453592 kg.

2. Consider an Atwood's machine consisting of two masses connected by a string which is over a pulley, as shown in the picture.

a) Draw a free body diagram for both block A and block B.

b) Apply Newton's second law to both block A and block B.

c) the mass of block A is 14 kg while the mass of block B is 6 kg, find the tension in the rope.

3. Consider a modified Atwood machine, with a mass sitting on a table connected by a string which stretches over a pulley connected to a hanging mass. Friction is ignored.

a) Draw a free body diagram for both block 1 and block 2.

b) Apply Newton's second law to both block 1 and block 2.

c) If the mass of block 2 is 20 kg while the mass of block 1 is 5 kg, find the tension in the rope.