Solving Uni Physics with Projectile Motion

[Stephen1993]

uni physics!

Homework Statement

A child runs down a 12 degrees hill and then suddenly jumps upward at a 15 degree angle above horizontal and land 1.4m down the hill as measured along the hill. What was the child's initial speed?

firstly, when he runs downhill with a certain velocity then how is that part of the component of velocity in the projectile motion? i am confused because the person jumps and so i wonder what happens to the velocity that the person has when he travels downhill
a diagram might help to explain things of what is happening like how the velocity that the boy runs downhill contribute to the velocity of the projectile motion.

thank you

 

[gneill]

Consider t = 0 to be when the child jumps and concentrate on the required trajectory from that moment. What "launch" velocity is required, with a 15° launch angle, to land 1.4m downslope?

 

[Stephen1993]

the trouble is how is the velocity that the person runs downhill related to the projectile motion?
because he jumps which means that he exert a force which makes him undergo projectile motion

ty

 

[gneill]

the trouble is how is the velocity that the person runs downhill related to the projectile motion?
because he jumps which means that he exert a force which makes him undergo projectile motion

Once you've got the launch velocity you can always break it down into components parallel to and normal to the slope, and assume that the action of the jump is to add the normal component to the initial downslope one.