A student tests the emission spectra of various known substances and an unknown substance. Which statement is a qualitative observation of the tests? A. Two emission lines were seen in the spectra between 400 and 500 nm.

B. The unknown substance contains barium ions.

C. Sodium produces a yellow flame when heated.

D. Nitrate ions have no effect on the color emission.

we need to know the time interval during which the force acts. impulse of force = momentum change

the design of a ski jumping suit involves a trade-off between giving the skiers lift to get higher jumps and ensuring the skier does not face a lot of drag before the jump itself. an expansive suit may to lift the skier higher, but at the same time, it will also increase the air resistance. higher air resistance as the skier goes down the slope limits the speed of the jump. a big suit also increases the risk of losing balance or control, especially if there's a strong gust of wind. while technologically enhanced suits a lot, clothing is not the only factor in a ski jumper’s success. gathering speed while skiing down the slope, ensuring good speed on the ramp, and maintaining good body posture and form in the air all contribute to a ski jumper's success.