A carbon steel ball with a 30mm diameter is pressed against a flat carbon steel plate with a force of 20n. calculate the diameter of the circular contact area and the maximum pressure that occurs at the center of the contact area

28,288.54N/m²

Explanation:

Given the diameter of the carbon steel = 30mm

If the carbon steel is pressed against a flat carbon steel plate with a force of 20N, the diameter of the circular contact area will be the same i.e the diameter of the carbon steel that came in contact with the area will imprint the same diameter of 30mm on the circular area.

The pressure exerted on the center on the contact area can be calculated using the formula;

Pressure = Force/Area

Where applies force = 20N

Area = πd²/4 where d = 30mm

d = 30/1000 = 0.03m(converted to meters)

Area = π(0.03)²/4

Area of the circular disc = 0.000707m²

Pressure applied = 20N/0.000707m²

Pressure applied = 28,288.54N/m²

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the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s