Recent content by lando45

Thanks. I will look into a vertical divider Regarding the plastic bottle suggestion, will the cooling effect of the ice not be quite significantly reduced if the ice is all enclosed in plastic?

Yep I'm with you there, having thought about it I don't see any benefit to adding salt I'm still interested in whether a smaller coolbox would make a difference, and also whether keeping the bedroom door/windows closed would help

That's helpful, thank you. So for a given volume of ice, the total "cooling power" is fixed. But the rate at which it's used is dictated by (among other things) the size/shape of the ice. So one big block would cool at the slowest rate (but would last longest), whereas the same block broken into...

Hi guys, I used to post on here quite a bit back in 2005-2007 when I was studying Physics in school, I remember it always being a great resource so hopefully I can get some similar help with this "real life" problem I'm having now! We are having a mini-heatwave here in the UK the last few...

Hi, I was trying to solve this question but my answer is different to the one given by my textbook. "The weight of a randomly chosen plastic washer is normally distributed with mean 5g. Calculate the standard deviation in grams given that the probability that a randomly chosen washer weighs...

Please can you clarify? I'm not sure what the difference between a false positive probability and a false negative probability is.

"Imagine there is some rare disease that only affects 1 in 10,000 people, but if you get it, it's completely fatal and there is no cure, death is guaranteed. One day you get really paranoid and decide to take a test to see if you have the disease or not, so you go down to your local doctor and...

Ah! So I need to add the radius of planet Earth to the overall radius?

"An Earth satellite moves in a circular orbit 730 km above the Earth's surface. The period of the motion is 99.2 min. What is the magnitude of the centripetal acceleration of the satellite?" OK so to solve this I used the formula centripetal acceleration = v^2/r To calculate velocity (v) I...

Ah OK. Well I did that and here's what I got: m1u1 + m2u2 = (m1 + m2)v (0.4 x 2.4) + (0.5 x 0) = (0.4 + 0.5)v 0.96 = 0.9v v = 1.067ms^-1 0.5mv^2 = 1.2J mv^2 = 2.4J v^2 = 2.4 / 0.9 = 2.67 v = 1.633ms^-1 Combined velocity = (1.067 + 1.633)ms^-1 = 2.7ms^-1 So then do I just...

When I first read this question I thought it would be simple to solve but apparently it's not, I'm having some difficulty with it. "Two blocks can collide in a one-dimensional collision. The block on the left hass a mass of 0.40 kg and is initially moving to the right at 2.4 m/s toward a...

EDIT: OK I just solved it, I realized I was using the wrong equation, I should have been using the differential of the y displacement function. Thanks anyway.

My teacher set us a bunch of pendulum/SHM questions, and I managed to crack them all except for this one which has been bothering me: "A 5.4 g bullet is fired horizontally into a 0.50 kg block of wood resting on a frictionless table. The block, which is attached to a horizontal spring...

Ah that clears things up, that's great thanks. OK I managed to do part b)i) it was deceptively simple, the answer was just the lowest value in the frequency range given (i.e. 4.00 x10^14 Hz). But I don't think that the answer to b)ii) will just be the highest value in the frequency range...

Hi, I got this question and I have spent a while trying to crack it but I'm still stuck. White light, with frequencies ranging from 4.00 x10^14 Hz to 7.85x10^14 Hz, is incident on a potassium surface. Given that the work function of potassium is 2.24 eV, find the following values. (a) the...