I need help on figuring out how to approach this physics problem please help?

Question

A skateboarder is perched at the top of a perfect half‐pipe on a perfect skateboard.
Cool, dude…except there is a trap door at the bottom of the curve! See figure. The trap door will trigger
if the force exerted down on it is greater than 1000 N. The radius of the semi‐circular half pipe is 3.4 m.
The total mass of skate boarder and skate boarder is 56 kg. The velocity of the skateboarder when he is at the bottom of the half-ipe is 2.44m/s

Use Newton’s 2nd law for the radial component and the speed in part 1 to find the apparent
weight (aka normal force) on the skateboarder at that instant. Does the trap door trigger?

how can I find the apparent weight someone please help?

Jánošík · Accepted Answer

There's somthing wrong with this question...
The say it's a perfect half-pipe and a perfect skate board, so you may assume there's no friction.

By conservation of energy:
Ep = Ek
m×g×h = m×v²/2
v = √(2×g×h)
v = √(2×9.8×3.4)
v = 8.16 m/s
That should be the velocity of the skater at the bottom of the half-pipe, but they say it is 2.44 m/s...

I need help on figuring out how to approach this physics problem please help?

1 Answer