The bell crank shown turns about the pin O. A vertical force of 250 N acts at A, 120 mm from O, and is balanced by a horizontal force Q at B, 150 mm above O. Find Q.
Frames & machines worksheet with answers
A hand squeezes the handles of a pair of pliers with 200 N each, 120 mm from the pin O. The jaws grip a bolt 20 mm from the pin. Find the gripping force Q on the bolt.
The A-frame shown stands on a pin at A and a roller at B, 4 m apart. The legs meet at the pin C, 2 m high, and the horizontal tie DE is 1.2 m above the ground. A load of 8 kN acts at C. 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 8 m apart, and B is 2 m above the ground and 4.8 m to the right of A. A vertical load of 12 kN acts on member AB at K, 2.4 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, 4.8 m apart, with its apex pin C 4.5 m high and the horizontal tie DE 1.5 m above the ground. A vertical load of 5 kN acts on leg AC at K, 1.2 m (horizontally) from A. Find the magnitude of the force C that the pin C exerts on leg BC.
The A-frame shown stands on a pin at A and a roller at B, 2 m apart. The legs meet at the pin C, 3.6 m high, and are tied by the horizontal bar DE at 1.5 m. A horizontal force of 8 kN to the right acts at C. Find the tension T in the tie.
Answer key
- 1. Q = 200 N
- 2. Q = 1200 N
- 3. C = 10.77 kN
- 4. FBC = 6.792 kN
- 5. C = 1.601 kN
- 6. T = 6.857 kN
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