Mechanical Engineering Answers

A truck and trailer must be able to accelerate at 0.3 m/s2 up an incline of 1 in 20. The truck’s engine generates a torque of 900Nm. It has a moment of inertia of 30kg.m2 . The efficiency of the truck’s transmission is 83%. The mass of the truck is 12 tons, and that of the trailer is 9tons. The tractive resistance for both the truck and the trailer combined is 60N/ton. The truck has 12 wheels and the trailer has 8 wheels. The wheels on both vehicles are identical. Each wheel has a diameter of 1.2m, a mass of 75kg and a radius of gyration of 500mm. Determine two suitable overall gear ratios. 

A mass of 9kg draws a second mass of 4.5 kg up a smooth 30° incline by a light cord passing over a smooth pulley. Find the velocities of the two bodies after they have moved a distance of 3m from rest(Use conservation of energy)

Clearly show the following values:

Direction of movement=??

Friction force=??

E_k=??

E_p=??

E_TR=??

E_TE=??

E_FRICTION=??

Energy Equation=??

V_A=??

V_B=??

A metal car starts from rest and slides 12 m down a chute that is inclined at 40° to the horizontal. It then continues to slide along a horizontal length of the chute and eventually comes to rest. If μ = 0,2 between the chute and the car, calculate the horizontal length of the chute. Use conservation of energy to solve this question.

Clearly show the following values in their respective sections

Section A:

E_k=?

E_p=?

E_TR=?

E_TE=?

Energy equation=??

v=??

Section B:

E_k=?

E_p=?

E_TR=?

E_TE=?

Distance=??

A light 300mm diamter pulley is held stationairy and carries a 10kg mass haning on a light cord passing around the pulley. Find the vertical acceleration of the mass when the pulley is released. Frictional torque is the pulley bearings is 3N.m.

Clearly show the following value

E_k=?

E_p=?

E=?

Energy equation=??

v=??

A tractive effort of 3kN drives a 5 ton truck from rest up an inclince of 1 in 40. If the tractive resistance is constant at 380N and the tractive effort is parralel to the plane of the incline, use the method of conservation of energy to calculate the speed of the trcuk after it has traveled 250m up the incline.

Clearly show the following values:

E_k=?

E_p=?

E_TR=?

E_TE=?

Energy equation=?

v=?

A train of mass 220 tonnes starts from rest up a grade of 1 in 90 incline. It reaches a speed of 72 km/hr in a distance of 900 m (up the incline). The acceleration is uniform and the tractive resistance is 0,75 % of the weight of the train. Use Newton’s second law to calculate the tractive effort required.

During your calculations clearly show:

a=?

TE=?

A weight of 20kg acts tangentially at a radius of 650 mm and causes a pulley to accelerate uniformly from 35 rev/min to 120 rev/min in 20 seconds. Calculate the work done and the average power required to cause this acceleration.

Clearly show the following values

wi=?

wf=?

θ=?

Torque=?

W=?

Pave=?

A spring of free length 240 mm is 200 mm long when carrying a compressive load of 50 N. When fully compressed, the spring is 110 mm long. Calculate the spring rate and the work done in compressing the spring from 175 mm long to 120 mm in length. 

Clearly show these values in your calculation

k=?

F1=?

F2=?

ave F=?

W=?

When a certain perfect gas is heated at constant pressure fr 15 degree C to 95 degree C, the heat required is 1136KJ/Kg.When the same gas is heated at constant volume between the same temperatures the heat required is 808KJ/Kg. Calculate the Cp, Cv, R and molar mass of the gas.

A thermocouple is used to measure the temperature of air flowing through a duct. The heat transfer coefficient between the air and the thermocouple is proportional to v0.8, where v is the average velocity of the air within the duct. Assume that the heat transfer by radiation from the duct walls to the thermocouple bead is linearly proportional to the temperature difference between them. For v= 5 m/s, the thermocouple reads 50