Answer:
If you try to lift up a weight in a swimming pool and then try to lift the same weight on the edge of the pool, it feels much lighter in the water.
This was supposed to have been first explained by the Greek scientist Archimedes. He said that the water gives an upward force or upthrust on any object in it.
You can weigh an object in air and then in water and actually work out the upthrust, it is the difference between the two readings. For this reason the upthrust is often called the loss in weight of the object.
Answer:
28.6 ohm
Explanation:
there is a 3rd resistor in series. voltage drop across the resistors will be equal to 60v
7*.2+7*.2 +.2x = 60
2.8+.2x = 60
.2x = 57.2
x = 28.6
Answer:
D
Explanation:
Look at the two of them, if you put them together the image is identical to that of the unknown sample.
Answer:
The two main categories of boat hull designs are;
- Displacement Hull
- Planning Hull
Explanation:
<u>Displacement Hull</u>
This type of boat hull is designed to displace certain amount of water as it moves. This displacement enable it to insert its body into the water and continue to displace water from its was as it moves. The weight of water displaced is usually equal to the weight of the boat.
Displacement Hull and Speed
Because of the need to displace water from its path to enable it insert itself into the water body for movement, the speed is usually slow compared to planning hull boats.
Displacement Hull Types:
- Round bottomed hull boat: Their hulls are made to have a round bottom in order to displace water and move smoothly through it. It can move quietly at low speed. How ever, they require complex stabilizer to control them from banking.
- Multi hull boat: This type of hull design has a large and long beam that make it to be very stable on the water body. They usually have ends pointed downwards for proper insertion and displacement. However, they don't turn easily on small space due to their large beam requirement.
<u>Planning Hull</u>
Planning hull boats are designed to slide very fasly on the water surface with very little or no insertion. They require boat engines that operates at a very high revolution per minute(rpm).
When at rest, that is at zero speed, they behave like displacement hull boats but only a small amount of water is displaced a they are usually lighter.
Planning hull boats can operate in three modes:
- Displacement mode: This mode is used when planning hull boats move at extremely slow speed. At this mode, they push water side ways as they move.
- Planning mode: This mode is activated as the speed of the boat increases to enable it glide on the surface of the water.
- Plowing mode: This mode is reach when the bow of the boat is trusted up and suspended as it slides through the surface of the water at a very high speed
Planning Hull and Speed
The speed of planning hull boats is very high when compared to displacement hull boats. This high speed of operation is powered by high rpm engines to enable it slide on the surface of the water.
Planning Hull Types/Merit and Demerit
- Flat Bottom Hull: Their hull is flat bottom shaped and has a draft that supports its suspension on water on a stable manner. Suitable for stable water. However, it moves haphazardly on shaky water.
- Deep Vee Hull: It has a V-shape hull that points towards the water body. Its V-shape makes it glide through rough water surfaces more smoothly than the flat bottom hull. However, it requires more power to operate and easily banks during sharp turning.
Gravity causes falling objects to accelerate.
