"if the end of the crutch is a circle of radius 1.2 cm without the tip, and the rubber tip is a circle of radius 2.3 cm , by what factor does the tip reduce the pressure exerted by the crutch? "

The pressure exerted by the crutch is reduced factor by 0.72.

Explanation:

Given that,

Radius of crutch = 1.2 cm

Radius of tip = 2.3 cm

We need to calculate the pressure without tip

Using formula of pressure

Put the value into the formula

....(I)

We need to calculate the pressure with tip

Using formula of pressure

....(II)

We need to calculate the reduction factor

Using formula of reduction factor

Put the value into the formula

Here, F is the same

The pressure exerted by the crutch is reduced by 72%.

Hence, The pressure exerted by the crutch is reduced factor by 0.72.

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