Question : Need to know how I would (descriptively) draw the Free body Diagram and how to calculate A net force of an object with more than 2 forces such as the questions below and most importantly how to get the final Direction. Explain in detail and show work please:
2. A tow truck is starting to tow a damaged car and exerts a force of 4000 N [E] on the car. A 1500 N [W] force of friction opposdes the car's motion. The force of gravity on the car is 8000 N [down].
a) Draw a Free Body Diagram for the ..
Answer : a) To draw a free body diagram, just draw a simple picture of a car (the tow truck is not needed, or it can be included if you want), the road. Then show gravity acting on the car with an arrow downward, show the force of the earth acting back on the car (the opposite and equal to gravity's force). This should go upward to the sky. Then arrow the force of friction going in the opposite direction of the car, and the force exerted on the car by the tow-truck as an arrow opposite to that of friction.
b) the force of gravity i presume is not important, so we use the east and west forces. Lets say the tow truck force is positive, thus: +4000N. It can also be said that the force of friction is thus negative: -1500N.
We can now add these forces:
4000 + (-1500)
= 4000 - 1500
= 2500N ------> this is the net force on the car. and as force is a vector, a direction must be given. the net force is positive (same as tow truck East), so thus the answer is: The net force is 2500N East.
Question : 1. The actual mechanical advantage of a machine
a. cannot be less than 1.
b. decreases as the input distance increases.
c. increases with greater friction.
d. is less than the ideal mechanical advantage of the machine.
2. If you have to apply 30 N of force on a crowbar to lift a rock that weighs 330 N, what is the actual mechanical advantage of the crowbar?
3. Reducing friction in a machine
a. decreases its actual mechanical advantage.
Answer : d.
Question : and what would be a good picture to represent static fiction? I found a picture of trying to push a heavy box, but since it was too heavy, there is no motion. Does this count as static friction? Also since we have to put arrows for direction of motion and friction, I would put and arrow saying 'static friction' and another saying 'intended motion', correct?
Answer : A man sitting on a hill or a box that is stationary on a ramp.