Mechanical Engineering Answers

An ac circuit consists of a resistance and capacitance connected in series. The result is that

A farm worker is exposed to Trifluralin, a commonly used pesticide, while working in the fields. Calculate the risk of the worker exposed to 0.01mg/m³ who works 8 hours per day, 7 days a week, for 4.0 months a year, and for 25 years. Assume a body weight of 70.0 kg and an inhalation volume of 20m³ per 8 hours. The slope factor for Trifluralin is 8.4 x 10-¹ (mg/kg. day)-1.

Listed below is a combination of stresses acting at a point and referred to axes x and y in an elastic material. Using Mohr’s circle of stress determine the principal stresses at the point and their directions for each combination.

i) sigma x=-60 N/mm^2, sigma y=-36N/mm^2, shear stress (xy) =5N/mm^2

ii) sigma x=30 N/mm^2, sigma y=-50N/mm^2, shear stress (xy) =30N/mm^2

In crank and slotted lever quick return mechanism, the crank length is (100 +X )mm and the distance between the fixed center is (225+X)mm. The length of the slotted lever is (525+X)mm. Determine the ration of time of cutting stroke to time of return stroke. Also calculate the length of the stroke .  

A person puts a few apples into the freezer at -12°C to cool them quickly for guests who are

about to arrive. Initially, the apples are at a uniform temperature of 30°C, and the heat transfer

coefficient on the surfaces is 21 W/m2·°C. Treating the apples as 9-cm-diameter spheres and

taking their properties to be ρ = 900 kg/m3, Cp = 3.81 kJ/kg·°C, k = 0.615 W/m·°C, and α = 1.4×10-7 m2/s, determine the center and surface temperatures of the apples in 1.5 h. Also, determine the amount of heat transfer from each apple. Use Heisler chart to solve the problem.

A force of 60 N is supported by the bracket as shown. Determine the resultant internal loadings acting on the section through point A.

A force of 60 N is supported by the bracket as shown. Determine the resultant internal loadings acting on the section through point A.

A gear with a width of 32 mm sits on a shaft with a diameter of 14 mm. The gear has a pitch diameter of 57 mm, the module 3 mm and a torque of 48 Nm. 

1.What width should a standard wedge have?

2, What height should a standard wedge have?

3, What will be the safety against surface pressure for a steel wedge?

4, What will be the safety against surface pressure for a cast iron wedge?

5, What is the safety against surface pressure for a fixed boom connection?

6, If the gear is allowed to move axially during operation, what is the safety against surface pressure for the boom joint then?

7,Before manufacturing the booms in the hub, a center hole must be drilled. What is the hub's largest possible hole diameter before boom production begins? 

A lamella coupling according to the figure below has friction surfaces between the diameters 135 and 105 mm. The coupling works with the surface pressure 36 N / cm2 and the friction number between the friction surfaces is 0.3. The lamella package is compressed by springs with the spring constant 610 N / cm per spring.

1. What force do the springs compress lamella packages with?
2. How much are the springs compressed?
3. Determine the transferable torque if we assume that the frictional force attacks the average radius

A scooter has hydraulic disc brakes both front and rear. The brakes have a brake piston on each side of the disc. The average radius of the blocks' contact with the disc is 10 cm, the piston diameter is 20 mm and the steel disc weighs 0.8 kg. The coefficient of friction between the coating and the disc is assumed to be 0.4. The scooter weighs 160 kg including the driver and the weight distribution is 50% front and 50% rear regardless of whether you brake or not. The wheelbase (the distance between the center of the front and rear wheels) is 1.37 m and the wheel diameter is 0.45 m. Assume that you only brake with the front wheel and that the friction number between the tire and the road surface is 0.9. Steel has a specific heat capacity of 450 J / (kg ° C).

1. What is the minimum possible braking distance (you brake so hard that the front wheel is on the verge of locking) when braking from 50 km / h to a standstill?