Turning Effects of Forces (CIE A Level Physics)

A 20 cm ruler is pivoted at its centre. Equal and opposite forces of magnitude 5.0 N are applied to the ends of the ruler, creating a couple as shown

What is the magnitude of the torque of the couple on the ruler when it is in the position shown?

A 10 cm beam is pivoted at its centre. Equal and opposite forces of 10 N pull the ends of the beam, creating a couple as shown.

What magnitude is the torque of the couple?

A 1 m long uniform beam is hung from the ceiling by a rope. and is balanced when a 20 g mass is positioned 30 cm from the rope as shown. 

What is the mass of the metre rule?

A door handle in the diagram below has a length 10 cm requires a force of 20 N to turn it.

If the handle breaks and the door must be opened using the axle of the handle, with a diameter of 0.5 cm, how much force is needed?

A car wheel nut can be loosened by applying a force of 310 N on the end of a bar of length 0.7 m as in X. A car mechanic is capable of applying forces of 650 N simultaneously in opposite directions on the ends of a wheel wrench as in Y.

What is the minimum length l of the wrench which would be needed for him to loosen the nut?

The diagram shows a solid cube with weight W and sides of length L. It is supported by a frictionless spindle that passes through the centres of two opposite vertical faces. One of these faces is shaded.

The spindle is now removed and replaced at a distance      to the right of its original position.

When viewing the shaded face, what is the torque of the couple that will now be needed to stop the cube from toppling?

A trailer of weight 30 kN is attached to a truck. The trailer is raised until it is held at 50˚ to the horizontal by a vertical force F as shown in the diagram.

The trailer is 2.7 m in length and the position of its centre of gravity G is a third of the length from the hinge at O.

What is the vertical force F applied to the end of the trailer?

A 1 m long uniform beam has a mass of 2 kg and has a further mass of 5 kg attached at the end. It is in contact with a wall on one side and is supported by a wire at an angle of 30° to the beam. The beam is in equilibrium. What is the tension, T, in the wire?

A beam of length L and weight w  is suspended from the ceiling by two ropes. One rope is attached at the leftmost point of the beam, the second at a distance of 2 m along the beam. A weight W is suspended from the beam at a distance d from one end of the beam. Which formula expresses the value of d that must be used to ensure that the tension in both ropes is equal?

The diagram shows a bow and arrow. The arrow is positioned at the centre, X, of the string of the bow stretched between points Y and Z. The string is pulled back such that the tension in the bowstring is 10 N. What force will accelerate the arrow in the direction of point A, when the string is released?