Formulas
What is the formula for displacement and what must be included with the units?
displacement = final position - initial position
direction needs to be included with the units
units = meter
what is the first step when solving a problem?
multiplying force, multiplying the distance, or changing the direction of the input force
define power
power is the rate at which work is done
what is the formula for velocity
V = change in position / change in time
units = m/s
how long will it take for a 1238 W motor to do 64,896 J of work?
52.42 seconds
compare and contrast a contact force with a field force. Give one example of each.
contact force is between two objects that physically touch each other. Field force is between objects that don't touch. contact force: friction and field force: magnetism
how do you gain mechanical advantage with gears?
similar to what happens with a wheel and axle, the change in diameter will give you a mechanical advantage. Gears can also change the direction of force
What is the formula for momentum?
P = mv (mass * velocity)
(kg*m/s)
average velocity
define acceleration
a vector quantity, is the change of velocity in a unit of time. units are m/s^2
Daniel applies a 471 N force 1.81 m to the right of the fulcrum of a seesaw, while Isaiah applies a 355 N force 2.25 m to the left of the fulcrum. Will the seesaw be in rotational equilibrium? Why or why not?
No, the system will rotate clockwise. Daniel is creating greater torque than Isaiah.
what is the law of torques?
F1L1 = F2L2 (force and length from fulcrum)
Units (N*m)
you are using a pulley system to lift 415N object to a height of 2.70m. If the IMA and AMA of the system are 5.0 and 4.61 respectively, what force must you apply and how far will you have to pull the rope?
F(in) = 90.0 Newtons;
d(in) = 13.5m
Define a newton / what is a newton? - not a fig newton :)
a newton is the unit for force. It's the force required to move 1kg, 1m in 1 second.
A single movable pulley has an IMA of two. What can you conclude about the pulley's AMA?
The pulley's AMA will be less than 2. WHY??
What is the formula for work? What is required for work to be done on a system?
W = force * distance (units Joule)
the object must move in the direction of the force applied. direction must be parallel to the force
why can a third - class lever have a mechanical advantage only between zero and one?
FRE - 123
since the effort or F(in) is in the middle, d(out) will always be larger than d(in). So the ratio of d(in)/d(out) will always be less than 1.
explain the law of torques
the law of torques states that if a system is in rotational equilibrium, then the sum of the torques must be zero (clockwise rotation must cancel out counterclockwise rotation). I will also accept if you say the two sides must equal each other.
First class - fulcrum in middle
second class - resistance in middle
third class - effort in middle