Question

To slow down a car, a braking force of $1200newtons$is applied for $10seconds$. How much force would be needed to produce the same change in velocity in $6seconds$ -

• A. $2000N$
• B. $3000N$
• C. $2500N$
• D. $1500N$

Answer 1

The correct option is A

$2000N$

Step 1: Given

For the case I, force, $F=1200N$ and time, $t=10\mathrm{s}$,
For case- II: time,$t=6\mathrm{s}$

Step 2:
By using the second law of motion,
$F=ma$
where F= force, m= mass and a= acceleration
$F=m\frac{v-u}{t}$
Where m is the mass of the car, v is the final velocity and u is the initial velocity of the car.
Case-I

$m(v-u)=Ft=1200\times 10\dots \left(i\right)$
Case- II
$F=m\frac{v-u}{t}$
by using equation (i)
$F=\frac{1200\times 10}{6}=2000\mathrm{N}$
Therefore, $2000\mathrm{N}$ the force would be needed to produce the same change in velocity in 6 seconds.