Q. In a uniform gravitational field of gravitational acceleration g', two particles move horizontally with initial velocities u1=3m/s and u2=4m/s in a direction opposite to each other. Find the distance of separation and time when their velocities are mutually perpendicular to each other.
1if they meet perpendicularly at time 't'
at that moment,
assuming that 1st was thrown in positive 'x' direction and 2nd was thrown in negative 'x' direction
v1 = 3 i + (-gt) j
v2 = -4 i + (-gt)j
also at that time 't'
v1.v2dot product = 0
ie,
-12 + g2t2 = 0
t = √12g
30Why would gravitational acceleration be perpendicular to the velocities if its a uniform gravitational field?
1because gravitational acceleration is in vertical direction and velocities are in horizontal direction
1ashish i didn't understand what u wanted to ask
If it is not perpendicular to it then you could have written it as any 'force field'
but writing 'GRAVITATIONAL field' itself tells us that it is perpendicular to horizontal direction of cartaesian plane.(unless any other dramatic condition is mentioned)
30Yes.. I get it! I was stuck with the word "uniform" for no reason! Thanks~! :)
71Don't think too much in a Problem.. It makes it complicated in no way. Many Students have these Problems though!