Using proper formulas, how do you go about with this question... really confused

1.) A sprinter accelerates from rest to 10.0m/s in 1.35s. What is her acceleration (a) in m/s^2 and (b) in km/h^2?

2.) A sports car is advertised to be able to stop in a distance of 50m from a speed of 90 km/h. What is its acceleration in m/s^2? How many g's is this (g=9.80 m/s^2)

a=changeveloicyt/time=10/1.35 m/s^2

To solve these problems, we can use the following equations of motion:

1.) For the sprinter:
a) The formula we can use is:
v = u + at

Where:
v = final velocity (10.0 m/s)
u = initial velocity (0 m/s since the sprinter starts from rest)
a = acceleration (what we need to find)
t = time (1.35 s)

Rearranging the equation, we get:
a = (v - u) / t

Substituting the given values, we have:
a = (10.0 m/s - 0 m/s) / 1.35 s
a = 7.41 m/s^2 (rounded to two decimal places)

b) To convert the acceleration from m/s^2 to km/h^2, we need to consider the unit conversions:
1 km = 1000 m
1 hour = 3600 seconds

We can convert the acceleration using the conversion factors:

a_km/h^2 = a_m/s^2 * (3600 s / 1 hour) * (1 km / 1000 m)

Substituting the value of a_m/s^2, we have:
a_km/h^2 = 7.41 m/s^2 * (3600 s / 1 hour) * (1 km / 1000 m)
a_km/h^2 = 26.77 km/h^2 (rounded to two decimal places)

2.) For the sports car:
The formula for acceleration is:
a = (v^2 - u^2) / (2s)

Where:
a = acceleration (what we need to find)
v = final velocity (0 m/s, since the sports car is stopping)
u = initial velocity (90 km/h)
s = distance (50 m)

First, we need to convert the initial velocity from km/h to m/s:
u = 90 km/h * (1000 m / 1 km) * (1 hour / 3600 s)
u = 25 m/s (rounded to two decimal places)

Now we can substitute the values into the formula:
a = (0 m/s)^2 - (25 m/s)^2 / (2 * 50 m)
a = -625 m^2/s^2 / 100 m
a = -6.25 m/s^2

To find the acceleration in g's, we divide the acceleration by the acceleration due to gravity (g = 9.80 m/s^2):
g's = a / g
g's = -6.25 m/s^2 / 9.80 m/s^2
g's = -0.64 g

So, the acceleration of the sports car is approximately -6.25 m/s^2, which is approximately -0.64 g.