DP Physics (last assessment 2024)
Question 18M.3.HL.TZ1.b
| Date | May 2018 | Marks available | [Maximum mark: 3] | Reference code | 18M.3.HL.TZ1.b |
| Level | HL | Paper | 3 | Time zone | TZ1 |
| Command term | Show that | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 3]
18M.3.HL.TZ1.b
The water supply for a hydroelectric plant is a reservoir with a large surface area. An outlet pipe takes the water to a turbine.
The water level is a height H above the turbine. Assume that the flow is laminar in the outlet pipe.
Show, using the Bernouilli equation, that the speed of the water as it enters the turbine is given by v = .
[3]
Markscheme
PS = PT «as both are exposed to atmospheric pressure»
then VT = 0 «if the surface area ofthe reservoir is large»
« + ρgzS = ρgzT»
= g(zT – zS) = gH
and so vS =
MP1 and MP2 may be implied by the correct substitution showing line 3 in the mark scheme.
Do not accept simple use of v = .
[3 marks]
