MOTION
- Q. When a car accelerates quickly, why are the people in the car forced backwards into the seat?
- A. Inertia is the tendency for an object at rest to remain stationary. The people in the car are still when the car accelerates and they have a tendency to remain still. The overall effect is to be appear to be thrown back into the seat.
- Q. Why does a moving skateboarder fly forwards when he/she collides with a gutter?
- A. Inertia is the tendency for a moving object to continue moving in the same direction at the same speed. The skateboarder continues with the same movement in spite of the skateboard being left in the gutter.
- Q. How can you tell the difference between a hard-boiled egg and a fresh egg by spinning each?
- A. The hard-boiled egg will spin faster than the raw egg.
- Q. Why is it dangerous to drop a pebble from the top of a tall building onto the footpath below?
- A. Gravitational acceleration on earth is about 10m/s2. This means that every second after the pebble has dropped its speed will increase by 10m/s. For example, after 1 second the speed will be 10m/s, after 2 seconds it will be falling at 20m/s, and after 10seconds it will be falling at 100m/s. That means that after 10 seconds, it could travel the length of an oval in 10 seconds. At speeds like that, a tiny pebble would be like a bullet when it hit the footpath.
- Q. What’s a ‘g’? How many g's can humans withstand before becoming ill?
- A. 'g' means gravitational acceleration of 9.8 m/s2. Rollercoasters usually have a maximum of about 4g, because people tend to vomit if it is more. Fighter pilots and astronauts tend to be able to withstand higher g's but there a limit at which they may black-out.
- Q. Should you walk or run in the rain to avoid getting wet?
- A. You will get equally wet.