Don't post anything unless it's the answeran object has an initial velocity of 15 m/s. how long must it accelerate at a constant rate of 3.0 m/s² before its average velocity is equal to twice its initial velocity? (hint: find a formula for average velocity first. do not confuse this with final velocity.) 5 s10 s15 s20 swhich of the following indicates the gravitational force on the balloon? *1 point(look at hot air balloon image below)5120 n950 n4050 n1520 na piano with a mass of 200 kg is suspended by a rope. what is the gravitational pull on the piano? 200 n853 n1962 n2017 na general orders a cannonball launched at a certain angle. four seconds after firing, it hits the top of a castle wall 500 meters away. the height of the wall is 50 m. at what angle did the general order the cannonball to be fired? 14º21º37º76º