Hi everyone ! My name is Sean. I'm a new member of this forum. I couldn't do any attempts for this problem. Actually, i did many attemps but they went wrong. 1. The problem statement, all variables and given/known data How can i solve this problem ? Your friend is late for school and is running with a speed of [itex]v_f[/itex] up a hill which makes an angle of [itex]\theta[/itex] with the horizontal. Just as he run for t seconds he realizes that he has forgotten his schoolbag at the foot o the hill where you are standing. He cannot come back and he must keep running. So you have to throw the bag to him with the largest possible speed you can achieve, which is [itex]v_b[/itex]. If he is still running up the hill what is the angle, [itex]\alpha[/itex] (measured with respect to the inclined plane) with which you should throw the bag to him if the bag is to reach him ? (Hint : Assume that [itex]\alpha[/itex] is small and use the necessary approximations to the trigonometric functions.) Thank you. Sean.