## Answer :

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-speed

Add start-speed to each side: start-speed + 15 m/s = 25 m/s

Subtract 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 speed

Moving at 25 m/s after gaining 15m/s ===> must have started out at

**.**

*10m/s*