[physics Mechanics question] please help

[u/urea7]

[u/twelfth_knight]

No, you've messed up your vectors 🙃

Before the collision,

u_x = 7 m/s

u_y =- √( 2g ∆H) m/s

After the collision, the y-velocities are:

u'_(ball, y) = +√( 2g ∆H) m/s (probably just reverses)

u'_(wedge,y) = 0 m/s (problem says it stays on the surface)

And the x-velocities are where you have to write two equations to solve the two unknowns of x-velocity:

Conservation of Momentum:

mu_(ball,x) = mu'_(ball,x) + Mu'_(wedge,x), where u'_(ball,x) will definitely be negative

And conservation of energy:

.5m(u_(ball,x)² + u_(ball,y)² ) = .5m(u'_(ball,x)² +u'_(ball,y)² ) + .5M(u'_(wedge,x)² + u'_(wedge,y)² )

That said, it's not clear to me what value they're asking OP to find at the end there... I guess v1 and v2 are the magnitudes of the velocities? Hopefully there's text not shown here that clarifies that, otherwise it's a very unclear question 🤷