A projectile is fired with velocity V making the angle x with the horizontal. what is the change in velocity when it is at the highest point?
At the highest point the velocity of the object will be u cos(x). And intially the velocity will be u. And u = root (u²sin²x+u²cos²x).
Now required ∆u= u cos x - u
Here we cannot say, because the horizontal component of velocity remains constant And only the vertical component of velocity changes, that u sin x vanishes, so ∆u=u sin x. Because u is not equal to u sin x + u cos x, but is equal to the resultant of u sin x and u cos x. But in the test in the projectile chapter my answer tuemed out to be Wrong. Why?