# In Need of Serious Help

1. Aug 28, 2005

### 4everYOURS

Ok there are three of us trying to figure out these problems and we just can't seem to figure out any of them so it'd be the greatest thing in the world if some one could enlighten us on what we're doing wrong. Here are the problems:

13. An astronaut drops a feather from 1.1 m above the surface of the moon. If the acceleration of gravity on the moon is 1.62 m/s2 downward, how long does it take the feather to hit the moon's surface?

2. A bike first accelerates from 0.0 m/s to 4.5 m/s in 4.5 s, then continues at this constant speed for another 3.5 s. What is the total distance traveled by the bike?

5. A horse canters away from its trainer in a straight line, moving 150 m away in 18.0 s. It then turns abruptly and gallops halfway back in 4.3 s.

Help would be sooo much appreciated.

2. Aug 28, 2005

### Fermat

13. use the suvat eqn of motion for distance travelled under a constant acceleration.

2. work out the acceleration during the first stage of movement, hence distance travelled.

5. there's no question.

3. Aug 28, 2005

### iNCREDiBLE

constant acceleration.

You need to use the following formula:
$$d = v_0t + \frac{at^2}{2}$$