More physics help(struggling)?

Question

DISTANCE- An in-line skater first accelerates from 0.0 m/s in 4.5 s , then continues at this constant speed for another 4.5 s. What is the total distance traveled by the in-line skater?

seriously need help please explain and solve. Thanks

Answer 1

First you have to find his acceleration in the first 4.5 secs...

v = u + at

5 = 0 +4.5a

a = 5/4.5 =1.11 m/s².

Then, to find the distance travelled in this time use v² = u² + 2aS

5² =0 + 2 x 1.11 xS

25 =2.22S

S = 25/2.22 =11.25m.

Distance travelled at a constant speed of 5m/s for 4.5s use S=vt

S = 5 x 4.5 =22.5m.

Total distance travelled = 11.5 + 22.5 = 34 m.

Answer 2

The first distance you have to figure out is the initial 4.5 seconds.  If he accelerated from 0 to 5 meters/second, his average speed for that time period was 2.5meters/second.  Therefore, he travelled 2.5m/s times 4.5s or 11.25 meters.  The second distance was a constant speed of 5m/s for 4.5s or 5 x 4.5 is 22.5meters.  You add those two together and you get a total distance of 33.75 meters travelled in the 9 seconds.

Answer 3

depends on acceleration. use formula vf^2=vi^2+2as for first part and s=1/2at^2+vit for second part. then just add them up.

make it a good day

Answer 4

You need to know either the acceleration a or the final velocity v.  If you know a, The distance traveled is

s = ½a*t1² + a*t1*t2,  where t1 is the time of the acceleration phase, and t2 the time of the constant speed phase.  (The speed in the constant speed phase is a*t1)

If you are given v, then a = v/t1 and use the above formula to get

s = ½(v/t1)*t1² + v*t2 = ½v*t1 + v*t2

EDIT:  From your added information, v = 5.0 m/s, so the second condition applies:

s = ½*5*4.5 + 5*4.5 = 11.25 + 22.5 = 33.75 m

Answer 5

During first 4.5 s: -

u = 0, v = 5.0 m/s, t = 4.5 s

Let s1 = distance

s1 = average speed * time = {(v + u)/2} * t = (5 + 0)/2 * 4.5 = 2.5 * 4.5 = 11.25 m

During constant speed: -

The skater runs at 5.0 m/s for 4.5 second

Distance s2 = 5 * 4.5 = 22.5 m

Total distance = s1 + s2 = 11.25 + 22.5 = 33.75 m

Ans: 33.75 m