The discussion revolves around calculating the initial velocity of a projectile launched at a 45-degree angle from a height of 1 meter, which lands 2.5 meters away at a height of 0 meters. A secondary scenario involves a massless ball that bounces before reaching its final landing spot, with an initial angle of -45 degrees. Participants explore whether these calculations can be made without knowing the time of flight.
The conversation is ongoing, with various participants offering insights and questioning the assumptions made in the problem. Some suggest using energy conservation principles, while others express confusion about the setup and the variables involved. There is no explicit consensus on the best approach, but several lines of reasoning are being explored.
Participants note potential typos in the problem statement regarding the mass of the projectile and the angles involved. There is also a recognition that the problem may require simultaneous equations to solve for the unknowns, particularly the point of bounce and the initial velocity.
rl.bhat said:Your formula for y is wrong. It should be
yf = yi + vt - 1/2*g*t^2.
physicskid69 said:I now use that velocity with yf=yi+vt+1/2gt^2 to solve for t where yf=0.1m and yi=0m. This gives me t=0.881s.
rl.bhat said:Yes. I didn't notice.
0.1 = 4.43*t - 4.9*t^2
Or 4.9*t^2 - 4.43*t + 0.1 = 0
When I solved it I got different answer. Check it.
rl.bhat said:You have taken two time intervals to calculate the time of flight, taking into account the bounce.
But the vertical space in only 1m!