Essay on Engineering Mechanics Revision Finals Exam

1487 Words Apr 24th, 2013 6 Pages
Problem Sheet No. 1

1. Determine the tension in cables CA and CB.
Ans. TCA = 2870 N, TCB = 3520 N.

2. The uniform bar has a mass per unit length of 60 kg/m. Determine the reactions at the supports.
Ans. Ay = 3060 N, By = 2060 N.

3. The uniform angle bar with equal legs has a mass of 20 kg and is supported in the vertical plane as shown. Calculate the force FA supported by the pin at A.
Ans. FA = 277 N.

4. Determine the reactions at A and E if P=500 N. What is the maximum value that P may have for static equilibrium? Neglect the weight of the structure compared with the applied loads.
Ans. Ax = -1290 N, Ay = 2960 N, E x= 3290 N, P=1732 N.
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In addition, calculate the force R which the ramp exerts on the cart.
Ans. P = 45.5 N, R = 691 N

The rear-wheel-drive car has a mass of 1400 kg with mass center at G. First calculate the normal forces under the front and rear wheel pairs when the car is at normal test. Then repeat your calculations for the case shown where the front bumper is tested by causing the car to push, via its rear wheels, against the fixed barrier with a 2500-N force. Neglect friction at the bumper-barrier interface, but not at the tire-ground interface.
Ans. Normally, NA = 6310 N, NB = 7430 N Under test, NA = 6720 N, NB = 7010 N

The bracket and pulley assembly has a mass of 40 kg with combined center of gravity at G. Calculate the magnitude of the force supported by the pin at C when a tension of 400 N is applied in the vertical plane to the cable. D is the point of attachment between the cable and the bracket. Is the result remains independent of the position of D?
Ans. C = 952 N

Figure P.S.1.13

Figure P.S.1.14

Figure P.S.1.15

Figure P.S.1.16
If the load on the crane is increased by 4 Mg, compute the corresponding increment (A in the force supported by the pin at A.
Ans. (A = 56.6 kN

Each of the structure is statically indeterminate. Describe at least one modification in the supports for each case which would make the structure statically determinate.


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