For the Titanic problem, draw more correlations with some parameters besides gender and class, and come up with a better predictor. Upload it on the website to test the prediction accuracy
Why does this happen? How do the two balls know they have to hit the ground at the same time?
Introduce the notion of horizontal and vertical motion being independent of each other
But why horizontal and vertical? How does the ball know what is horizontal and what is vertical?
We could have chosen any two directions and it would still work - the reason we take horizontal and vertical is because gravity is acting vertically and no force is acting horizontally (ignoring air friction)
If you were in a car and you threw a ball straight up, would the ball return to your hand, or ahead or behind? Air resistance can be ignored
v=u+at, s=ut+(1/2)at^2. Breaking u into u.sin@ and u.cos@ (if kids do not know trigonometry, just do u1 and u2.
Show an example of a ball thrown horizontally at 5m/s at 10m height and 10m/s^2 gravity. Do the computation on time to hit the ground, distance traveled, velocity at impact
If we had thrown the ball from point of impact with velocity of impact, where would it land? Reversibility of path.
If we had just dropped the ball, what would be the time to impact? Same as throwing the ball horizontally.
Now, if we dont throw is horizontally, but at an angle upwards from the ground?
We already know what happens on the reversed path. And then the ball will be horizontal and look like its been thrown horizontally from there on
What if we were throwing at an angle but not from ground, but from 10m above ground? Break up the path in two segments - before and after highest points.
When you toss a coin, what happens? (The center of gravity is in projectile motion, and the coin spins around that)
Misslies
Escape Velocity
What will happen if you throw something up with a lot of force? What if you applied even more force?
How far does the earth's gravitational field last? International space station is 400km from earth; Moon is 400,000km from earth, and they still feel the gravity though its 0.03% of what we feel on earth
Why don't they fall to the earth then? Idea of orbits and how ISS can keep falling but stay in orbit.
Can we launch something with enough force for it to "escape" the earth's gravitation?
Escape velocity of earth is 11.2 km/sec
Rockets routinely launch and escape surface of earth. Normally they don't launch at 11.2 km/sec, but have booster stages that fire at different points in their journey.
And they don't need to go straight up, we can use the velocity due to earth's rotation to assist
And we can put them in a temporary orbit, and then fire from there - again leveraging the orbital velocity
Gravitational slingshot
Gravitational slingshot is a mechanism to use gravity of a planet to speed up (or decelerate) a spacecraft, without using energy. It can also be used to change direction.
Luna 3 (1959) was the first mission to use gravity assist to photograph far side of moon
Homework:
Hang a hoop on the ceiling at your house. Now throw a ball so that it passes through the hoop. Now hang another hoop behind the first one (at last two feet apart) so that the ball can now pass through both the hoops (you can use this as a game in your school fair)
