If the forces acting on an object are balanced, what is that objects acceleration?

The roller coaster from problem #1 then tops a second hill at 15.0 m/s, how high is the second hill? 91.5 m 79.2 m 80.0 m 68.5 m

4. if you were an astronaut on the moon, what would you experience? what would you see from your perspective?

Mark saxby is set to kick the field goal to win the state championship for olathe east. he is 47m away from the goalposts, and he kicks the ball at a speed of 25.0m/s at an angle of 30.0°. if the cross bar on the goalposts is 3.00m above the ground, will the ball make it over the cross bar? and if it does make it, by how much will it clear?