Question

Q3. Calculate the work required to be done to stop a car of 1000 kg moving at a velocity of 20 km/h?​

Answer 1

$\large \rm {\underbrace{\underline{\dag{Elucidation:-}}}}$

$\sf \red {\underline{\underline{\maltese{Provided\: That:}}}}$

→Mass of the car(m)=1000kg

→Velocity of the car(v)=20km/h

~We need to convert the above given unit(km/h) into m/s . The given quantity should be multiplied by the fraction $\sf {\frac{5}{18}}$ in order to be converted into m/s.

$\large \sf \mapsto {20×\frac{5}{18}}$

→Velocity of the car(v)=5.56m/s

$\sf \blue {\underline{\underline{\maltese{To\: Determine:}}}}$

→Work done to stop a moving car.

~The point to be recollected here is , As the car is in motion it possess kinetic energy and since we need to stop a moving car the work done is stored in the form of kinetic energy.

$\sf \pink {\underline{\underline{\maltese{Formula:}}}}$

$\large \implies {\boxed{\frac{1}{2}mv^{2}}}$

$\sf \purple {\underline{\underline{\maltese{Substitution:}}}}$

$\large \mapsto {\frac{1}{2}×1000×(5.56)^{2}}$

$\large \mapsto {\frac{1}{\cancel{2}}×\cancel{1000}^{500}×30.9}$

$\large \mapsto {500×30.9}$

$\large \sf \implies \green {\boxed{\underline{15,450J}}}$

$\sf \orange {\underline{\underline{\maltese{Therein,}}}}$

→Work required to be done to stop a car is 15,450 Joules respectively.

$\mathbb {\underline{\underline{\maltese{NOTE:-}}}}$

→The answer may vary depending upon the consideration of the numbers after the decimal point . However , the answer might not differ much except there'll be a slight change in the last digit of the answer .