The bell crank shown turns about the pin O. A vertical force of 200 N acts at A, 180 mm from O, and is balanced by a horizontal force Q at B, 80 mm above O. Find Q.
Frames & machines worksheet with answers
A hand squeezes the handles of a pair of pliers with 120 N each, 150 mm from the pin O. The jaws grip a bolt 18 mm from the pin. Find the gripping force Q on the bolt.
The frame shown has pins at A, B and C; A and C are fixed to the ground 4 m apart, and B is 2 m above the ground and 1.2 m to the right of A. A vertical load of 15 kN acts on member AB at K, 0.48 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, 4 m apart, with its apex pin C 2.4 m high and the horizontal tie DE 0.8 m above the ground. A vertical load of 12 kN acts on leg AC at K, 1.5 m (horizontally) from A. Find the tension T in the tie.
A uniform horizontal boom AB of weight 1 kN is pinned to a wall at A and held by a cable from its end B to the point C on the wall, 2.5 m above A. A load of 8 kN hangs at B. Find the tension T in the cable.
A uniform horizontal boom AB of weight 1.5 kN is pinned to a wall at A and held by a cable from its end B to the point C on the wall, 4 m above A. A load of 12 kN hangs at B. Find the tension T in the cable.
Answer key
- 1. Q = 450 N
- 2. Q = 1000 N
- 3. FBC = 3.097 kN
- 4. T = 5.625 kN
- 5. T = 19.01 kN
- 6. T = 15.94 kN
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