Question

Find the distance travelled by the truck during that interval.

Answer 1

Given mass of the box = $40$ kg , kinetic friction ${\mu }_k$=0.2, acceleration a=$5m/s^2$ and displacement of the box = $6$ m

Now force exerted on the box due to acceleration of the truck

F=mass$\times$acceleration=$40\times 5=200$ N

Now the friction force acting on the box $f=\mu mg$ where $\mu$= kinetic friction

$f=0.2\times 40\times 10=80$ N

Thus net force on the block $F_{net}$=$F-f$

$F_{net}$=120 N

Now acceleration produce during the backward motion of the block

$a_{back}=\frac{F_{net}}{m}$

$a_{back}=3m/s^2$

From equation of motion

$s=ut+\frac{1}{2}a{t}^2$

$t^2=\frac{12}{3}$

$t=2s$=time of falling the object from the rear end

Now distance traveled by the truck in $2$ seconds

$s=ut+\frac{1}{2}a{t}^2$

$s=5m$