The bell crank shown turns about the pin O. A vertical force of 50 N acts at A, 200 mm from O, and is balanced by a horizontal force Q at B, 150 mm above O. Find Q.
Frames & machines worksheet with answers
The handles of a pair of pliers are squeezed with 200 N each, 150 mm from the pin O, and the jaws grip a wire 35 mm from the pin. Take all forces as perpendicular to the handle. Find the force FO that the pin transmits.
The A-frame shown stands on a pin at A and a roller at B, 3 m apart, with its apex pin C 2.5 m high and the horizontal tie DE 0.6 m above the ground. A vertical load of 5 kN acts on leg AC at K, 0.9 m (horizontally) from A. Find the tension T in the tie.
The frame shown has pins at A, B and C; A and C are fixed to the ground 6 m apart, and B is 3 m above the ground and 0.9 m to the right of A. A vertical load of 10 kN acts on member AB at K, 0.225 m (horizontally) from A. Find the force FBC in member BC.
The A-frame shown stands on a pin at A and a roller at B, 2 m apart, with its apex pin C 3.6 m high and the horizontal tie DE 1.2 m above the ground. A vertical load of 4 kN acts on leg AC at K, 0.6 m (horizontally) from A. Find the magnitude of the force C that the pin C exerts on leg BC.
The frame shown has pins at A, B and C; A and C are fixed to the ground 5 m apart, and B is 2 m high and 2.25 m to the right of A. Member AB carries a vertical load of 5 kN at K, 0.9 m (horizontally) from A, and a horizontal load of 6 kN to the right acts at B on member AB. Find the size of the horizontal reaction Ax at A.
Answer key
- 1. Q = 66.67 N
- 2. FO = 1057 N
- 3. T = 1.184 kN
- 4. FBC = 0.7396 kN
- 5. C = 1.3 kN
- 6. Ax = 1.463 kN
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