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Physics Guru is an online education and competitive examinations preparation portal founded by Manish Verma, an IIT Madras alumnus, providing learning resources for competitive examinations.

The emphasis is on conceptual understanding, analytical thinking and problem solving rather than simply memorising formulas and standard methods.

The objective is to help students understand what they are learning and develop the ability to solve problems they have not seen before.

Projectile Motion Problem & Solution

Problem

A student sits atop a platform a distance h above the ground. He throws a large object horizontally with a speed u. A wind blowing parallel to the ground gives the object a constant horizontal acceleration with magnitude a. This results in the object reaching the ground directly under the student. Determine the height h in terms of u, a and g. Ignore the effect of air resistance on the vertical motion.

Solution

Image(2)

For vertical motion,

$h = \frac{1}{2}g{t^2}$............*

For horizontal motion,

$0 = ut + \frac{1}{2}( - a){t^2}$

or $0 = u - \frac{1}{2}at$..............#

Putting $t = \sqrt {\frac{{2h}}{g}}$ from * in #,

$0 = u - \frac{1}{2}a\sqrt {\frac{{2h}}{g}}$

or $h = \frac{{2{u^2}g}}{{{a^2}}}$.