Question

A projectile is fired from the surface of the earth with a velocity of $5m{s}^{-1}$ and angle $8^{\circ }$ with the horizontal. Another projectile fired from another planet with a velocity of $3m{s}^{-1}$ at the same angle follows a trajectory which is identical with the trajectory of the projectile fired from the earth. The value of the acceleration due to gravity on the planet is: $(given=9.8m{s}^{-2})$

• A. $3.5$
• B. $5.9$
• C. $16.3$
• D. $110.8$

Answer 1

The correct option is A $3.5$

For same trajectory both should have same horizontal range and maximum heights

$⟹\frac{5^2}{g}=\frac{3^2}{a}$

$⟹a=9.8\times \frac{9}{25}$

$a=3.5$