# 查看完整版本 : IGCSE's physics question

hyman9090 2018-4-2 08:52 PM

## IGCSE's physics question

A particle of mass M, which is subject to a constant resisting force, is observed to cover distances of s_1 and s_n respectively in the first and nth seconds of its motion. Find an expression in terms of s_1 and s_n for the magnitude of the resistance force.

[[i] 本帖最後由 hyman9090 於 2018-4-2 08:55 PM 編輯 [/i]]

chess8 2018-4-3 08:15 PM

S1 is average velocity in the first second.(距離除以時間，時間係1秒)
Sn is average velocuty in the nth second.
Change of average velocity is s1-sn
time for the change is n-1 seconds

hyman9090 2018-4-4 03:54 AM

chess8 2018-4-5 06:04 AM

hyman9090 2018-4-5 04:12 PM

concept 完全明, 我就係用F=ma, 但就係揾唔到答案

chess8 2018-4-5 04:54 PM

chess8 2018-4-5 05:56 PM

a等於 (v-u)/t

a等於(sn-s1)/(n-1)

F等於M(s1-sn)/(n-1)

hyman9090 2018-4-7 11:44 PM

s=ut+(1/2)at^2

chess8 2018-4-12 04:53 PM

[quote]原帖由 [i]chess8[/i] 於 2018-4-3 08:15 PM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=477913279&ptid=27350614][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]
S1 is average velocity in the first second.(距離除以時間，時間係1秒)
Sn is average velocuty in the nth second.
Change of average velocity is s1-sn
time for the change is n-1 seconds

chess8 2018-4-14 12:31 AM

hyman9090 2018-4-15 01:37 AM

chess8 2018-4-15 06:44 PM

hyman9090 2018-4-16 12:30 AM

chess8 2018-4-16 12:58 AM

hyman9090 2018-4-16 11:35 PM