Chapter 8: Practicals_checked

Question 1

How do you measure the motion of a trolley in an experiment with light gates?

How can you reduce error in final result?

Answer 1

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
2. Light gates have an infrared beam that’s interrupted by the trolley’s card
3. Light gate is connected to a data logger which will measure the time it takes for the whole card to get through the beam
4. Use equation change in s(width of card) / change in time to get v
5. 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

1. Cupcake cases are greatly affected by air resistance
2. By measuring displacement, time, height of drop over which the case is falling, you can investigate the factors such as mass that affect terminal velocity

Question 3

How do you 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 (for example). 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