ch8 practicals

Question 1

how to measure motion of a trolley in an experiment with light gates

how can you reduce error in final result

Answer 1

set up apparatus as shown

release trolley and it will accelerate down slope, easy to find s and t, but you need light gates to find velocity v

light gates have an infrared beam that’s interrupted by the trolley’s card

the light gate is connected to a data logger which will measure the time it takes for the whole card to get through the beam, use equation change in s(width of card) / change in time to get v

repeat experiment for a certain distance 3 times and average results to reduce error in final results

Question 2

briefly describe set up to check terminal velocity for a cupcake case

Answer 2

cupcake cases are greatly affected by air resistance

by measuring displacement, time, height of drop and over which period of the case falling you rae timing you can investigate the factors such as mass that affect terminal velocity

Question 3

how to measure acceleration due to g

Answer 3

use equation s = ut + 1/2at²

dropped from rest so u = 0 and a = g so use s = 1/2gt² and we know s

set up as shown

steel ball held by electromagnets, when it’s turned off, ball falls and breaks contacts at the top starting a timer. falls until it hits contacts at trap door and breaks them stopping the timer

Question 4

define standing waves

Answer 4

transmitted wave reflected at boundary with a 180 degrees phase change. transmitted and reflected waves superpose creating nodes and antinodes. at certain frequencies positions of nodes and antinodes are constant, resulting in a standing wave

Question 5

phasors have the same frequency as the wave and amplitude of wave is the length of the phasor