Question

A car of mass 1500-kg starts from a speed of 18m/s and reaches a speed of 28 m/s in 4s. Find the average force.

Answer 1

The average force is given by the following formula:

`F=ma`

where m is the mass of the car (1500 kg) and a its acceleration. To calculate the acceleration use the following expression:

`a=(v-v_o)/(t)`

where,

v: final speed = 28m/s

vo: initial speed = 18m/s

t: time of the acceleration = 4s

Replace the previous values into the formula for a and simplify:

`a=(28(m)/(s)-18(m)/(s))/(4s)=(10)/(4)(m)/(s^2)=2.5(m)/(s^2)`

Next, replace the previous value of a and the mass m into the expression for F and simplify:

`F=(1500kg)(2.5(m)/(s^2))=3750N`

Hence, the average force of the car is 3750N