PHL105Y5 Lecture : Hobbes and Rawls

Please help with these questions !!&lt;br /&gt;<BR>1. A rope is towing a 100 kg rock, from rest, with a force of 10 N that varies with time. At the end of 8.0 sec, the velocity of the rock is?&lt;br /&gt;<BR>Answer is: zero&lt;br /&gt;<BR>&lt;br /&gt;<BR>2. A 3 kg mass is positioned at (0,8) and a 1 kg mass is postioned at (12,0). What are the coordinates of a 4 kg mass which will result in the center of the mass of the system of three masses being located at the origin (0,0)?&lt;br /&gt;<BR>The answer is (-3,-6)&lt;br /&gt;<BR>&lt;br /&gt;<BR>3. A car traveling 20 m/s rounds an 80 m radius horizontal curve with the tires on the verge of slipping. How fast can this car round a second curve of radius 320 m? (assume the same coefficient of friction between the car's tires and each road surface).&lt;br /&gt;<BR>The answer is: 40 m/s&lt;br /&gt;<BR>&lt;br /&gt;<BR>Thanks !! <BR>

A ceiling fan has five blades, each with a mass of 0.34 kg and a length of 0.66 m. The fan is operating in it&amp;#39;s &amp;quot;low&amp;quot; setting at which the angular speed is 9.4 rad/s. If the blades can be approximated as uniform thin rods that rotate about one end, what is the total rotational kinetic energy of the five blades?

1. can increase the speed of a moving particle.
2. can cause a moving particle to accelerate.
3. always exerts a force on a moving particle.
4. can exert a force on a stationary particle.

choose any of the answer below:
a) 2 & 4
b) 2
c) 2 & 3
d) 1 & 2
e) 3