Question

A frictionless wagon going at$2.5meters$ per second is pushed with a force of $380\mathrm{N}$, and its speed increases to $6.2meters$ per second in$4.0seconds$. What is its mass -

• A. $410\mathrm{kg}$
• B. $420\mathrm{kg}$
• C. $480\mathrm{kg}$
• D. $310\mathrm{kg}$

Answer 1

The correct option is A

$410\mathrm{kg}$

Step 1: Given data.

Initial velocity, $u=2.5\mathrm{m}/\mathrm{s}$, force, $F=380\mathrm{N}$, final velocity, $v=6.2\mathrm{m}/\mathrm{s}$, and time, $t=4\mathrm{s}$

Step 2: Calculations.
Using the first equation of motion
$v=u+at=2.5+a\times 4$
$6.2-2.5=4a$
$a=0.925\mathrm{m}/{\mathrm{s}}^2$
$F=ma⟹m=\frac{F}{a}=\frac{380}{0.925}=410.8\mathrm{kg}$
The mass of the wagon is $=410.8\mathrm{kg}$.