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物理 · 共 13 題 · 點擊選項即時核對答案

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11.

Light rod PQRST with equally spaced points: 1 N upward at Q, 2 N downward at R, 1 N downward at S

The diagram shows a light rod under the action of three vertical forces. The points $P$ , $Q$ , $R$ , $S$ and $T$ are equally spaced along the rod. At which point must an upward vertical force of $2$ N be applied to hold the rod in equilibrium ?

12.

Uniform metre rule hung by a string with tension T, a 6 N weight 30 cm from the left end and a weight W at the right end, the string 20 cm from the 6 N weight

In the figure shown, the uniform metre rule of weight $1$ N is balanced horizontally. Find the tension $T$ in the string.

13.

Light rod with a 2 kg mass at the left end, fulcrum F 2 cm from it, then points P (1 cm from F), Q (1 cm further) and R (2 cm further)

If a mass of $2$ kg is placed a distance of $2$ cm from the fulcrum $F$ as shown in the diagram, which of the following cases could keep the light rod in equilibrium ?

(1)a mass of

4

kg placed at

P

(2)a mass of

2

kg placed at

Q

(3)a mass of

1

kg placed at

R