Question

The equation of projectile is $y=8x-\frac{5x^2}{2}$. The horizontal range is-

• A. $8\text{m}$
• B. $3.2\text{m}$
• C. $8.4\text{m}$
• D. $2\text{m}$

Answer 1

The correct option is B $3.2\text{m}$

Equation of projectile is given by $y=x\tan \theta (1-\frac{x}{R})$
$y=x\tan \theta -\tan \theta \frac{x^2}{R}$
Here $R$ is Range of projectile.

Given that $y=8x-\frac{5x^2}{2}$
Compare from eqn.
$\tan \theta =8$ and $\frac{\tan \theta }{R}=\frac{5}{2}$
$R=\frac{16}{5}=3.2\text{m}$
$R=3.2\text{m}$