Review of Physics 2 - Exam
Semestr: sommer, 2019/20, Tutor: Martin Žáček, Date: 2020-07-03
For every task is for correct general result 1 point, for correct numerical result 1 point and correct way of solution for 3 points, i.e. maximum of possible points is 5 per task and maximum 20 points for the test. Numerical results estimate with the 1-digit of precision.
Task 1 - Water flowing out of a vessel
A vessel is filled with water to the height h=0.5 m. At the bottom is connected a horizontal tube consisting of two parts. The first one has cross-section S1=1 cm2, the second one S2=0.5 cm2 and its end is open so water can flow freely out of the vessel (see picture).
- Calculate the speed v of the outflowing water at the end of the tube.
- Calculate the pressure p in the first part of the tube.
Task 2 - The seconds pendulum
The seconds pendulum is a pendulum whose length is set so that the period is equal to 2 seconds.
- Calculate the length of the seconds pendulum, assume gravitational acceleration as g=10 ms−2.
- Calculate the total energy of the second pendulum, if the mass is equal m=2 kg and the initial deflection is φ0=2°
- What is the ratio of the lengths lE/lM and total energies EE/EM for pendulums located on Earth and the Moon with equal initial deflections φ0=2°? Assume the ratio of accelerations as gE/gM=9.81/1.62=6.056≈6.
Task 3 - Capacitors
Three capacitors with capacities C1=5 μF, C2=3 μF and C3=2 μF are connected serio-paralell where the first one is connected paralel with the remaining two, which are connected in series (see picture). Initially, the capacitors were not charged. Then was connected to a source with voltage U=10 V.
- Calculate the total capacity.
- Calculate the voltage at the capacitor C3.
- Calculate the total bound charge of all capacitors.
Task 4 - Weight of the atmosphere
From the pressure acting to the Earth's surface calculate
- The total weight m of the atmosphere.
- The total amount of matter s of the atmosphere.
- The total amount of particles N in the the atmosphere.
- The teoretical height h of the the atmosphere with assumption that their concentration n=N/V=const.