She is going 66 miles per hour.
As you know, speed is usually measured in miles per hour. The distance between the 88 mile marker and the 121 mile marker is 33 miles. That means Sara’s mom travelled 33 miles in 30 mins. You want to figure out how many miles she travelled in 60 minutes.
If she travelled 33 miles in 30 minutes, and 60 minutes is double 30 minutes, then Sara’s mom was traveling 66 miles per hour.
Answer :
(a) The initial velocity is, 14.8 m/s
(b) The acceleration is, 
Explanation :
By the 1st equation of motion,
...........(1)
where,
v = final velocity = 0 s
u = initial velocity
t = time = 6.35 s
a = acceleration
The equation 1 will be:

..........(2)
By the 2nd equation of motion,
...........(3)
where,
s = distance = 47 m
Now substitute equation 2 in 3, we get:

By solving the term, we get:

The acceleration is, 
Now we have to calculate the initial velocity.
Using equation 2, we gte:



The initial velocity is, 14.8 m/s
Answer:
The coefficient of rolling friction for the tire under low pressure is 0.0342.
Explanation:
Two bicycle tires are set rolling with the same initial speed of 4.00 m/s
Final speed of both the bicycle, speed is reduced by half is measured, v = 2 m/s.
Here,

Using third equation of motion as :

So, the coefficient of rolling friction for the tire under low pressure is 0.0342.