Question

The amount of force needed to change velocity of an object of mass 20Kg from 18Km/hr to 54km/hr in 10 seconds is​

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Answer 1

To find:

The amount of force needed to change velocity of an object of mass 20Kg from 18Km/hr to 54km/hr in 10 seconds.

Calculation:

u = 18 km/hr = 18 × (5/18) = 5 m/s

v = 54 km/hr = 54 × (5/18) = 15 m/s

So , applying 1st Equation of Kinematics:

$v = u + at$

$= > 15 = 5 + a(10)$

$= > 10a = 15 - 5$

$= > 10a = 10$

$= > a = 1 \: m {s}^{ - 2}$

Now , force is given as the product of mass of object and acceleration of object;

$\therefore \: force = mass \times (a)$

$= > \: force =( 20 \: kg )\times (1 \: m {s}^{ - 2} )$

$= > \: force = 20 \: kg m {s}^{ - 2}$

$= > \: force = 20 \: N$

So, final answer is:

$\boxed{ \rm{ \red{\: force = 20 \: N }}}$