Question

7. A boy is swinging on a swing such that his
lowest and highest positions are at heights of
2m and 4.5m respectively. His velocity at the
lowest position is,​

Answer 1

Answer:

Velocity at the lowest position is 7 m/s

Explanation:

At the lowest point, the total Potential energy will have converted into Kinetic energy

Potential energy at the highest point, taking 2 m as the lowest level

$P=mg(h_2-h_1)$

$\implies P=mg(4.5-2)=mg\times 2.5$

$mg\times 2.5=\frac{1}{2}mv^2$

$\implies v^2=2.5\times 9.8\times 2$

$\implies v^2=\frac{25\times 49\times 4}{100}$

$\implies v=\frac{5\times 7\times 2}{10}$

$\implies v=7$ m/s

Hope this helps.