mechanics

lkhj2525

1. A smooth block of mass 2 kg slides down a
wedge. The wedge, of mass 10 kg, is placed on
a horizontal table, and its inclined plane makes
an angle of 30º with the horizontal. If the
wedge remains stationary all the time, the
normal reaction of the table acting on the
wedge is
A. 15 N.
B. 85 N.
C. 100 N.
D. 115 N.
E. 120 N.

2.A smooth block of mass 2 kg slides down a
wedge with constant velocity. The wedge, of mass 10 kg, is placed on
a horizontal table, and its inclined plane makes
an angle of 30º with the horizontal. If the
wedge remains stationary all the time, the
normal reaction of the table acting on the
wedge is
A. 15 N.
B. 85 N.
C. 100 N.
D. 115 N.
E. 120 N.

第1條俾你地玩下
第2條可唔可以解釋點解係E

§阿虛§

我黎頂下板....

講下笑....
雖然我唔係好識...
不過剩係見到 with constant velocity...
咁姐係 net Force on the wedge by the block = 0 by Newton's first law....
然後...簡單的用 Normal reaction = mg = (10+2) x 10 = 120N...

我知咁樣解法係好有問題....不過0係毫無頭緒之下都撞到個答案出黎 =.=
請問第 1 條個答案係咩？ @"@
我亦想知第 2 條0既解法 /.\

韓信

我黎頂下板....

講下笑....
雖然我唔係好識...
不過剩係見到 with constant velocity...
咁姐係 net Force on the wedge by the block = 0 by Newton's first law....
然後...簡單的用 Normal reaction = mg = (10+ ...
§阿虛§ 發表於 10-4-2009 00:39

NET FORCE IS A DEFINITION ACCORDING TO 2ND LAW
NORMAL REACTION=20+100=120

§阿虛§

NET FORCE IS A DEFINITION ACCORDING TO 2ND LAW
NORMAL REACTION=20+100=120
韓信 發表於 10-4-2009 00:47

係啵 = =
我將前後掉轉左....
1st law 係 Fnet = 0         =>      change in velocity = 0  /.\

wilson1993912

請問wedge點解?= =

Roy

請問wedge點解?= =
wilson1993912 發表於 10-4-2009 12:53

楔形物,是楔形狀的物體

===
小弟有興趣知道第1題是否C。

wilson1993912

楔字點解???????= =

§阿虛§

其實唔需要知實際係點解...
通常哩一類都係講一舊野...
放左0係個斜面到...

我想知第 1 條0既計法同諗0既方法 =.=

§阿虛§

其實唔需要知實際係點解...
通常哩一類都係講一舊野...
放左0係個斜面到...

我想知第 1 條0既計法同諗0既方法 =.=

Roy

楔字點解???????= =
wilson1993912 發表於 10-4-2009 23:41

嗯...如樓上所言
「楔」其實是類似一個斜台的東西。

===
其實,
小弟都想了解第一題的解法。
希望有心人能作解答之。