Question

given calculate the force exerted by the brakes on the motor car which is moving with a velocity of 72 km/ and takes 5s to stop after I application of brakes. mass of the motorcar along with the passengers is 800 kg​

Answer 1

Answer:

the force needed is 3200N

• (convert velocity into m/s )
• later divide the velocity by time to get acceleration
• then multiple the mass and acceleration

Answer 2

ㅤㅤㅤEXPLANATAION :-

• Initial velocity of a car is 72 km/hr
• After application of brakes it came to rest i.e Final velocity of a car is 0 m/s
• Time taken is 5 s
• Total mass is 800 kg

Force exerted ?

As we know that,

Force exerted by body is given from Newton's second law .

${\boxed{ \boxed{</strong><strong>F</strong><strong> = \dfrac{m(v - u)}{t} }}}$

Where,

• F = force exerted
• m = mass
• v = final velocity
• u = initial velocity
• t = time

Converting km/hr - m/s for initial velocity of body :-

u = 72 km/hr

u = 72 × 5/18 m/s

u = 20 m/s

• u = 20 m/s
• v = 0
• t = 5
• m = 500 kg
• f = ?

$F = \dfrac{800(0 - 20)}{5}$

$F = \dfrac{800( - 20)}{5}$

$F = 800( - 4)$

${ \boxed {\boxed{F = - 3200N}}}$

So, force exerted by body is -3200N

Here ' - ' sign indicates in opposite direction.