CH6, 7, 8 and trig mixed Flashcards
Where is the hypotenuse?
It is the longest side. Always the side across from the right angle. It is the diagonal.
If you drag a block 20m with 5N or force, how much work did you do?
100 newton meters, or 100 JOULES
Where is the “adj” side?
if you imagine standing in a triangular room in the same corner as the angle. The adjacent side is the side you can touch that is not the hypotenuse. It makes the angle with the hypotenuse.
mv = Ft what does this say?
It is FAT MAV without the deltas
How much energy in a 4kg block traveling 3 m/s
KE = mv2/2 = 4*3^2 / 2 = 36/2 = 18 J
What does the delta triangle mean?
It means “CHANGE IN”
When you fire a gun, the force on the bullet is equal to the _____________
force on the gun
How do yu find the side furthest from the angle (opposite the angle) if you have the hypotenuse?
hyp * sin angle
How are FORCE and MOMENTUM different?
Force = mass (acceleration) where Momentum = mass (velocity). Momentum is present when an object is moving at a constant speed, Force needs acceleration to be present.
there are ______ of FORCE, ____ of WORK ,______ of POWER and _____ of ENERGY
NEWTONS of force, JOULES of work, WATTS of power and JOULES of energy
What do the interior angles of a triangle add up to?
180 degrees, since a right triangle already has a 90 degree angle, the other two angles are complementary (add to 90)
When a cannon is fired, explain how momentum is preserved.
mv(cannon) + mv(ball) before is ZERO. It has to be zero after, so the momentum the cannon moves must be opposite the momentum of the ball to cancel it out, so they must have the same magnitide. so after the cannon fires, MV (cannon) = MV (cannonball).
When you fire a gun, the momentum of the bullet just after the shot is equal to____
the momentum of the gun right after the shot.
What are the units of ENERGY?
JOULES - think of it as “work waiting to be done” or “stored work”
Which causes more impulse, a 1kg ball hitting you at 10m/s and falling, or a ball bouncing off your head and traveling back at 5 m/s?
A ball bouncing causes more of an impulse. Impulse is change in momentum. The ball that stops velocity only changes 10m/s (from 10 to 0), the bouncing ball goes from +10m/s to -5m/s, an overall change of 15m/s. The more the velocity changes, the more the momentum changes, which is a larger impulse!
How much power if you move 50 kg 20 meters in 10 seconds?
P = Fd / t = 50*20/10 = 100 WATTS
if force = mass * acceleration, then mass=
FORCE / ACCELERATION
Explain WORK units three ways
JOULE, or Nm, or kg*m2/ s2
What is the unit of work we use?
JOULE (newton*meter)
What is work?
FORCE X DISTANCE (in the direction of the applied force). Measured in JOULES
If two objects have the same velocity, the one with the larger mass has _____ momemtum
larger
What is “FAT MAV?”
F delta T = m delta v (force * change in time = mass * change in velocity)
You lift 8kg up 5 meters, How many JOULES?
400 Joules
When you have sides of a triangle, but are trying to find out what an angle is, what do you have to use?
trig -1 (untrig, inverse trig, arctrig)
What is kinetic energy?
one half mass velocity squared. MOVING energy.
What types of collisions do we usually consider when solving problems in class?
We assume they are elastic collisions (similar to how we often ignore friction).
sin f / cos f = tan ___
f
sin 70 = cos __
20
How to solve triangles when there are no angles given?
PYTHAGOREAN THEOREM
* BONUS*
If a 1 kg ball moving at 20m/s makes a 2cm dent in a wall. What was the force?
using F = m (delta v / delta t). We have m= 1kg, delta v = 20m/s- 0= 20m/s all we need is time. To find time, you need to user d = VT , or T = D/V… in this case, average velocity is (20 + 0)/2 = 10m/s .. so T = .02m/ 10m/s = .002 sec.
What are the three possible situations when solving trig ratios?
- solving for angle: trig x = A/B just untrig: X= trig-1 (A/B)
- solving for numerator: trig angle = X/B just slide the B: X= B trig angle
- solving for denominator: trig angle = A/X just switch: X = A/(trig angle)
F = ma can be changed to what?
change the a to (delta v / delta t) so you get: F = m (delta V / delta T)
this is another version of fat mav.
What is a way to think of mass when it comes to movement?
MASS RESISTS ACCELERATION (this is what we call inertia)
If you have a force and need to find the X and Y component, how do you do it?
The force given is always the hypotenuse of a right triangle. So draw an X and a Y component (a triangle). The closest (adjacent) side use FORCE * COS (ANGLE) and for the far (opposite) side use FORCE * SIN (ANGLE).
What are the two energies we talk about in this unit?
Potential (height) and Kinetic (speed)
What is an inelastic collision?
When some momentum, some energy is lost through heat, sound, etc
What are the three conservation of momentum equations we use in this class? (along with the situations
mv+mv= mv + mv (separate before and after). (m+m)v = mv + mv (stuck before). mv+mv= (m+m)v (stuck after)
How to solve for x: trig angle = X/B
SLIDE: B trig angle = x
If something is moving at a constant velocity, what do we know about force and momentum?
At constant velocity, a body is in equilibrium (all the forces cancel out). Because it is not accelerating, the net force is ZERO. But, because it is moving, there is momentum