Question

Ques1: .Fielder ‘F’ threw a cricket ball at a constant speed of 15 m/s and hit the stumps from a distance 30 m. The batsman ‘B’ was 15 m from the stumps and had an initial speed of 6 m/s when ‘F’ threw the ball. If ‘B’ ran with an acceleration of 1.0 m/s2, determine if ‘B’ would be ‘run out’.?
Ques 2:. If a 25 kg load is applied on Spring A, it elongates 0.25 m, but it elongates 0.30 m after being attached to another Spring B in series. Determine the spring constant of both springs.

Answer 1

1.

$$t=\frac{30}{15}=2\ s$$

$$d=vt+0.5at^2=(6)(2)+0.5(1)(2)^2=14\ m.$$

$d$<D=15 m. Thus, ‘B’ would not be ‘run out’.

2.

$$k_a x_a=mg$$

$$k_a=\frac{mg}{x_a}=\frac{(25)(9.8)}{0.25}=980\frac{N}{m}$$

$$K=\frac{mg}{X}=\frac{(25)(9.8)}{0.3}=817\frac{N}{m}$$

So,

$$\frac{1}{K}=\frac{1}{k_a}+\frac{1}{k_b}$$

$$\frac{1}{817}=\frac{1}{980}+\frac{1}{k_b}$$

$$k_b=4900\frac{N}{m}$$