Turning Effect of Forces

Describe a method used to draw these two lines in their correct positions on the card.

Make clear what extra apparatus is needed. You may draw a diagram, if you wish.

Explain why the card falls anticlockwise when $\theta$ is large.

State one change to the card that makes it more stable.

State what is meant by centre of mass.

______

State two features of the design that make the car in Fig. 2.1 stable.

1. ______
2. ______

Fig. 2.2 shows an irregularly shaped piece of card.

Describe how to determine the position of the centre of mass of the piece of card.

You may draw on Fig. 2.2 or in the blank space.

Calculate the maximum moment about the axis that this force can produce.

moment = ______

The moment produced by the nurse is less than this maximum value.

Suggest one reason why this is so.

State how the force needed to operate the tap is affected by the length of the handle.

State the principle of moments for a body in equilibrium.

Calculate the reading on the newton meter.

reading = ______

The weight of the metre rule is 1.2 N.

Calculate the size of the force exerted on the metre rule by the pivot.

force = ______

Calculate $W$.

$W$ = ______

The girl and her brother slide equal distances along the see-saw away from each other.

Describe and explain what happens.

Describe an experiment to verify the principle of moments. You may include a diagram in your answer.

Fig. 1.1 shows a spanner tightening a nut.

A force of $8.0\ \text{N}$ is applied to the spanner at a perpendicular distance of $0.15\ \text{m}$ from the centre of the nut.

Calculate the moment of the force acting on the nut.

moment = ______

State the principle of moments.

The maximum weight of a suitcase that can be carried onto the aeroplane is $67\ \text{N}$.

Determine whether the weight of the suitcase exceeds the maximum allowed.

Show a calculation in your answer.

State what is meant by the 'centre of gravity' of an object.

When the slope is made very steep, the bus falls over by rotating about point P.

Explain why the bus falls over.

Fig. 8.1 shows a force $F$ acting on an object at point P. The object is free to rotate about an axis at X that is perpendicular to the page.

Write down an expression for the moment of $F$ about the axis at X. Draw on Fig. 8.1 to show what is meant by any other term used in your expression.

State the principle of moments.

Describe an experiment to verify the principle of moments. Include a diagram to help the description.

State what is meant by centre of mass.

The centre of mass of the ladder is a horizontal distance of $0.90\text{ m}$ from the worker's shoulder.

Calculate the moment about the worker's shoulder of the weight of the ladder.

moment = ______

A bucket of weight $87\text{ N}$ is suspended from the ladder at a horizontal distance of $1.3\text{ m}$ from the worker's shoulder.

The worker keeps the ladder horizontal by exerting a vertical force at point L. L is a horizontal distance of $0.54\text{ m}$ from his shoulder.

Determine the size and direction of the force exerted at L.

size of force = ______
direction = ______

State the principle of moments for a body in equilibrium.

______

Determine the reading on the newton meter shown in Fig. 3.2.

reading = ______

A beaker of water is placed so that the brick is partly submerged in the water, as shown in Fig. 3.3. The apparatus is adjusted to keep the rule horizontal.

Suggest why the reading on the newton meter is less than your answer in (b)(ii).

______

State the principle of moments.

Determine the size of the total upward force exerted on the bed by the two legs when the bed is horizontal.

total force = ______