Amy

How can I calculate the efficiency of a centrifugal water pump when the power is not known?

I've had a lecture where we discussed randomised controlled trials and our lecturer asked us to search why if the actual treatment drug is given instead of a placebo pill by mistake (assuming it's the control group) the research is not affected. I could not find anything on the internet. Does someone know how to explain this?

I've got this sample paper and a movement is given and I have questions about it. It consists of a Menuet I and Menuet II. What period does this fall in? I could not find specific information on 2 Menuets.

In the past year, I have been playing the piano at our local hospital and I was not doing bad. But now it seems that I do not want to return to it. I always find excuses not to go, I do not want to prepare pieces to go. I just do not see the point of it going there, playing there etc. I have another hobby which I'm starting to grow fond of more and it is ballet. I also am studying at University. Whenever I try to prepare songs to go play at the hospital, I feel really bad and anxious - it's like I don't want to perform but still then I feel bad because I feel like I'm wasting my talent. I don't know what to do. Any advice?

I believe I saw pictures of her pregnant but I don't remember any news concerning her birth or any pictures of her child.

It says in my notes that the aorta gives off arteries to the head, neck and upper limbs. So what gives off arteries to the rest of the body?

I've got this sentence in my lecturer's notes saying:

"Proof of Heart: Complete innervation of the heart does not stop the heart from beating e.g. Heart Transplants."

Doesn't innervation mean to supply with nerves? So what do nerves have to do with it?

I'm in grade 8 piano and I saw this grand piano in the foyer in hospital and on it there was written that whoever wants to play it, may contact this person. So I did and he told me I can go to play whenever I wanted. I told him I can go on Monday and now I think this is all a huge mistake. I get so anxious playing in front of people and the thing is, I don't think I'll be prepared by Monday. I mean I prepared the list of songs I'm playing and all that but when I play them at home, I'm making some mistakes because the thing is at home I don't play music for an intended audience. I usually play my exam pieces, do a lot of exercises and play some music which is not properly fit for a hospital theme. So I don't know what I should do. I've been practicing a lot these 2 days. Do you think I should tell him to play on a later date to be more prepared? Or should I not even consider the idea at all because I am really really anxious and might mess up.

What is the difference between the root-mean-square speed and the mean speed of a group of gas molecules?

A glass bulb of 100 cm^3 is connected to another bulb of 200 cm^3 by a narrow tube of negligible volume. The apparatus contains air at 17 degrees celsius and 90.0 kPa pressure. The smaller bulb is then maintained at 57 degrees celsius, the temperature of the other bulb remaining at 17 degrees celsius. Calculate the new pressure in the apparatus. (Hint: the total number of moles in the two bulbs remain constant)

Answer: 93.8 kPa

A steel wire AB, length 1.000m and cross-section area 8 x 10-7 m^2 is joined to an iron wire

BC, length 1.500 m and cross-section area 6 x 10-7m^2.

The total length increases by 0.020m when a tensile force is applied along ABC.

If Young modulus of steel is 2.0 x 10^11 Pa and that of Iron is 1.2 x 10^11 Pa, find:

(i) the extensions of AB and of BC,

(ii) the common tensile force applied.

Answers: (i) 4.6 x 10^-3 , 1.5 x 10^-2

(ii) 738 N

A mobile robot is to be driven by a permanent magnet motor, which runs off a 12 V battery of negligible internal resistance. The resistance of the motor's armature winding is 7.5 ohms. When the motor is off-load (not driving the robot), it consumes a current of 0.16 A while rotating at a speed of 3000 revs per minute. Calculate the current through the motor armature and the power dissipated as heat when the motor shaft is prevented from rotating.

Why is it necessary to use the root-mean-square velocity to represent the average speed of the molecules?

A person is talking just behind the edge of an open door. Explain why he can be heard, even though he cannot be seen? What would be the effect if the open door were very wide?

A frictionless piston of diameter 0.05 m encloses a gas in a well lagged cylinder. When a 6 V DC heating element is switched on at a constant current of 0.3 A for 5.5 s, the piston is found to move a distance x. The process is reversible adiabatic.

a) If 6.85 J of the energy supplied by the heater is absorbed as internal energy of the gas, find the energy available for doing work against the external pressure.

b) If the external pressure is 10^5 Pa, what is the value of the distance x moved by the piston?

Two light strings are perpendicular to each other and support a particle of weight 100 N. The tensions in one of the strings is 40.0 N. Calculate the angle this string makes with the vertical and the tension in the other string.