PHYSICS: ACCELERATION QUESTIONS
1) An egg is thrown vertically downward from a window. If the egg was released with a velocity of 10.0m/s and it strikes the ground at a velocity of 25.0 m/s, how long did it take the egg to reach the ground ?
2) An object is dropped from the roof of a building. If the object takes 2.5s to reach the ground, what was the velocity of the object when it reached ground?
Thank you so much. :P
And for this question
An object accelerates uniformly at a rate of 1.50m/s^2 [E] for 10.0s. If the velocity of the object reaches 25.0m/s [E] at this time, what was the initial velocity?
Apparently the answer for that is 10.0m/s [E], but I keep getting -10.0
Thank you so much to anyone who could help!

1). The 'acceleration due to gravity' is about 9.8m/s².  That means that the downward speed of a a falling object increases by 9.8 m/s every second it falls.The egg was thrown downward at 10 m/s, and was falling at 25 m/s when it went splat on the ground.  Gravity increased its speed by (25 - 10) = 15 m/s.  That takes (15/9.8) = 1.53 seconds. 2).  The 'acceleration due to gravity' is about 9.8m/s².  That means that the
downward speed of a a falling object increases by 9.8 m/s every second
it falls.After falling for 2.5 sec, its downward speed is (2.5 x 9.8) = 24.5 m/s faster than it was when the object began falling.3).  The 'acceleration due to gravity' is about 9.8m/s².  That means that the
downward speed of a a falling object increases by 9.8 m/s every second
it falls.(Have you noticed a pattern among these questions yet ?)Acceleration = (change of speed) / (time for the chage).change of speed = (end speed) minus (start speed) = (25m/s - start speed).Acceleration = (25m/s - start speed) / (time for the change)          1.5 m/s² = (25m/s - start speed) / (10 sec)Let's multiply each side by  10sec :    15 m/s = 25m/s - start-speedAdd  start-speed  to each side:    start-speed + 15 m/s = 25 m/sSubtract  15 m/s  from each side:  Start-speed = (25-15) m/s = 10 m/s========================Quicker & easier way:(Caution ... requires thinking)Accelerate uniformly at 1.5 m/s² for 10 sec ===>  gain 15 m/s of speedMoving at  25 m/s  after gaining 15m/s  ===> must have started out at 10m/s.