4.10

SooHyun

SooHyun Lee
11P
Bangkok Patana School
________________________________________
From: Soo Hyun Lee
Sent: 07 September 2011 14:08
To: soohyunphysics@posterous.com
Subject: 4.10 ((nogallery))

· 4.10 understand that work done is equal to energy transferred

PFY p.112

[cid:image001.png@01CC6D66.70900440]
1. a) The work done (measured in Joules) is equal to the force (in Newtons) mutiplied by the distance moved (in metres).
b) 1 Joule is the work done when a force of one newton moves through a distance of one metre in the direction of the force.
c) Work done = energy transferred

[cid:image002.png@01CC6D66.70900440]
2. Wd = F x d
= 5N x 2 metres
= 10 Joules

[cid:image003.png@01CC6D66.70900440]

Wd = F x d
= 500 N x 40 m
= 20000 Joules = 20kJ

ke converted to heat and gpe

Collins p. 91

[cid:image004.png@01CC6D66.70900440]

Wd = F x d
50000J = F x 400kg
F = 125N

w = mg
400 x 10
4000N
W = Fd
50000J = 4000 N x d
d = 12.5m