# GATE Mechanical Exam Practice paper - 2 Online Test

Water (Cp = 4.18 kJ/kg.K) at 80°C enters a counterflow heat exchanger with a mass flow rate of

0.5 kg/s. Air (Cp = 1 kJ/kg.K) enters at 30°C with a mass flow rate of 2.09 kg/s. If the effectiveness

of the heat exchanger is 0.8, the LMTD (in °C) is

A solid circular shaft needs to be designed to transmit a torque of 50 N.m. If the allowable shear

stress of the material is 140 MPa, assuming a factor of safety of 2, the minimum allowable design

diameter in mm is

A box contains 4 red balls and 6 black balls. Three balls are selected randomly from the box one

after another, without replacement. The probability that the selected set contains one red ball and

two black balls is

In a DC arc welding operation, the voltage-arc length characteristic was obtained as

Varc = 20+5l where the arc length l was varied between 5 mm and 7 mm. Here Varc denotes the

arc voltage in Volts. The arc current was varied from 400 A to 500 A. Assuming linear power

source characteristic, the open circuit voltage and the short circuit current for the welding

operation are

In a single pass rolling process using 410 mm diameter steel rollers, a strip of width 140 mm and

thickness 8 mm undergoes 10 % reduction of thickness. The angle of bite in radians is

Calculate the punch size in mm, for a circular blanking operation for which details are given below.

Size of the blank 25 mm

Thickness of the sheet 2 mm

Radial clearance between punch and die 0.06 mm

Die allowance 0.05 mm

A room contains 35 kg of dry air and 0.5 kg of water vapor. The total pressure and temperature of

air in the room are 100 kPa and 25°C respectively. Given that the saturation pressure for water at

25°C is 3.17 kPa, the relative humidity of the air in the room is

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