CH 2, 3, 4 and 5 mixed Flashcards
A plane traveling north at 300 km/h airspeed hits southerly wind of 300 km/h. What is landspeed?
- It will look like it is standing still in mid-air
what are the angle measures of a 1-1-root 2 triangle?
45 -45- 90 across from those sides respectively)
How is velocity different from speed?
50 m/s is a speed. 50 m/s NORTH is a velocity. Velocity is speed with direction.
If you are given a force and a mass, you can find ____ by using the equation ____
a = F/m
A plane traveling north at 300 km/h airspeed hits southerly wind of 50 km/h. What is landspeed?
250 km/h
When a bullet leaves a gun, explain why the bullet moves faster forward than the gun moves backward
bullet has small mass, lots of accelertion, gun has lots of mass, little acceleration
What is acceleration when 12N is applied to 3kg object? Why?
4 m/s2
If you have weight, how do you find directional force?
w*sin(angle) gives the directional force
Which is more stable, mass or weight? Explain
mass is same on earth or moon, weight changes
Discuss the vertical component of a thrown baseball
The vertical component is impacted by gravity, so always changing by 10m/s per second.
Suppose you know the hypotenuse and the measure of an angle, and want to find the side across from the angle, on the opposite side?
hypotenuse x SIN (angle) [sin finds opposite side]
What is Newton’s First Law?
Object stays at rest, or moves at a constant velocity in a straight line unless a force acts on it.
A plane traveling north at 300 km/h airspeed hits northerly wind of 50 km/h. What is landspeed?
350 km/h. The wind speed adds to groundspeed
What are the side lengths of the 45-45-90 triangle?
1, 1 and sqrt 2
When have you felt acceleration?
In a car when you speed up (pulled back), slow down (pulled forward) or turn (pulled away from turn direction).
About how fast do people run in m/s? (mph?) [km/h?]
4-6 m/s (9 - 15 mph) [ 15- 20 km/h]
a newton divided by acceleration (m/s2) will give you
mass (kg)
How much does a 3kg object weigh?
about 30N
If you drop a ball from rest, how far did it go after 1s ? 2s ? 5s?
distance is always “avg velocity times time” From rest we can say “distance = 5t2” So, 5m, 20m, 125m
SATELLITES: If an object falls at about 5 m in first second, and the earth curves about 5m every 8km. How fast would something have to travel horizontally to never hit the earth?
8km/s (neglecting air resistance)… now you orbit :)
SATELLITES: How many times does the international space station orbit the earth each day?
It circles the earth every 90 minutes, about 16 times a day!!
What are the side lengths of the 30-60-90 triangle?
1, sqrt 3 and 2
About how fast do people walk in m/s? (mph?) [km/h?]
1-2 m/s (2-5mph) [3-6km/h]
How can we add two vectors (find resultant) by sketching?
Use the parallelogram rule, and the DIAGONAL is the resultant vector when both components start from the same spot.
Give a quick summary of Newton’s three laws of motion:
FIRST: objects in motion or rest stay that way, SECOND: a = F/m , THIRD: action have equal opposite reactions
How do we make sure our calculator is in the right mode?
press MODE> put cursor on DEGREES> press ENTER
How can you think about the horizontal and vertical speeds of a projectile? (shadows)
For Vx, the horizontal, imagine the sun straight above and visualize the speed of the shadow cast on the ground. the speed of the shadow is the horizontal speed. For Vy, the vertical speed, imagine a huge spotlight behind where the projectile is being launched from, pointing in the direction of the projectiles path. Also imagine a wall just beyond it. the speed of the shadow of the ball on that wall is the vertical speed.
What is difference between vector and scalar quantities?
Vectors have magnitude and direction, so combining them is tricky. Scalars have magnitude only, so they can be easily added, subtracted, multiplied and divided.
a mass (kg) multiplied by an acceleration (m/s2) will give you
a newton (force)
Give examples of scalar quantities.
mass, time, volume, area.
Suppose you know the hypotenuse and the measure of an angle, and want to find the side close to the angle, how do you do it? how do you find the close side?
hypotenuse x COS (angle) [cosine finds the close side]
What did Galileo discover from ramps and marbles?
That the distance an object travels, due to gravity, is directly related to the SQUARE of the time it travels.
What is the difference between mass and weight?
mass is the amount of stuff, weight is the force on the planet it is on
How fast is the fasted human in m/s? (mph?) [km/h?]
over 10 m/s ! (25 mph +) [35 km/h +]
Explain why a projectile is traveling slowest at the top
We know the horizontal component is always the same, so that will always be contributing, but the vertical component becomes ZERO at the top. You can visualize this by imagining a ball thrown straight up.. it stalls at the top for a split second.
If you drop a ball from rest, what is avg speed after 1s ? 2s ? 5s?
avg speed = (start speed + end speed) / 2 From rest we can simply say “avg speed= 5 t” So…. 5m/s, 10m/s and 25 m/s
What is an interesting fact about horizontal ranges and angles (when kicking a soccer ball or firing an arrow?)
Complementary angles (angles that add to 90) have the same horizontal range. EXAMPLE: kicking a ball at 30 degrees will go the same distance as 60 degrees (neglecting air resistance. Shooting an arrow at 10 degrees will travel the same horizontal distance as one shot up at 80 degrees!!!
What has to be happening in order for net force to not be zero?
it must be ACCELERATING (changing velocity). just moving is not enough, it has to be changing speeds!
How fast do cars travel in m/s? (mph?) [km/h?]
15 m/s backroad, 30 m/s on highway (35 mph and 70 mph) [50-100 km/h]
If you throw a ball up at 80m/s, how long till it reaches the top?
8 seconds
If you are driving at 40 km/h and speed up to 60 km/h over 10 seconds, what was your acceleration?
Your speed changed 20 km/h over 10 seconds, so (20 km/h / 10 s) = 2 km/h/s. You increased your speed 2 km/h each second.
Directional force is:
Fd is directional, or down the plane, parallel to the plane, along the plane
Describe what NET force is
the resultant force after you consider the combination of all the forces acting on an object
If you throw a ball straight up, what is the acceleration at the very top?
10 m/s2 this acceleration is forever present at the earth’s surface
SATELLITES: How much does the earth curve over 8 km?
about 5 meters
Give an example of Newton’s third law in real life:
the floor is pushing up on you as much as you are pushing down on the floor
SATELLITES: How far up is the international space station?
400 km (250 miles)
block on inclined plane: What is Fd and FN?
Fd is force down plane along the slope, FN is normal force directly into the plane