Recent content by Doyouevenlift

My attempt was just using kinetic energy, and my question was why the answer sheet has taken velocity to the third power, which hasn't been answered yet.

That's why I asked it, you arrogant person.

A rescue helicopter of mass 810 kg, supports itself in a stationary position by imparting a downward velocity, v, to the air in a circle of radius 4.0 m. The density of the air is 1.20 kg m-3. Calculate: (i) the value of v (ii) the power, P, required to support the helicopter So, I do...

But why? It the wreck tries to pull the car out of the water, I'm assuming there still is an upthrust while it is in the process of being pulled out. Yet, there must be some sort of change in extension, because pulling it out of the water still requires a force, eventhough there might be an...

Sounds logical, but what is then the justification of using the upthrust as the force required to pull the wreck out of the water? Intuitively, I'd say that you just subtract the upthrust from the car's weight (using w=mg), to get the force required. I always thought that things weigh less under...

So if I get this right: The upthrust equals the gravitational pull. Once it is cleared from the water, the upthrust is removed so the same force needs to be created by the machine?

[b]A submerged wreck, mass 104 kg and mean density 8 x 103 kg m-3, is lifted out of the water by a crane with a steel cable 10 m long, cross-sectional area 5 cm2 and Young’s modulus 5 x 1010 N m-2. Determine the change in the extension of the cable as the wreck is lifted clear of the...

1. A frying pan, weighing 2kg (heat capacity = 490 J/kg/K) and at a temperature of 70C is plunged into a bowl containing 4kg of water (heat capacity = 4200) at 20C. Assuming the bowl has negligible heat capacity and assuming that there is no heat flow to or from the surroundings, what is the...

Ok, thanks for the help

But what do they mean by 'mark the angles'. How can you know how big the angles actually are?

So how many lines would you have to draw? I'm guessing 3, one to the top of the eye, one to the dot and one to the bottom, but that seems so random.

1. Make a sketch copy of the diagram below and indicate clearly the position and nature of the image formed by the mirror. Draw rays corresponding to light coming from the open circle, and mark any relevant angles. You can see the picture they mean in the attachment. 3. My attempt at the...