A2000-kilogram car uses a breaking force of 12000 newton’s to stop in 5 seconds. what impulse acts on the car?

i honestly don't even know but yahoo answers says :

Impulse causes momentum to change, which means:  

Impulse = change in momentum, or in equation form:  

F∆t = (mv)2 – (mv)1  

so p (impulse)= mass times velocity so the mass is 2,000kg and the velocity is 12,000N/5s.  

speed is basically velocity so you have to calculate how many newtons per one second, so 12,000/5s-- just divide the numerator and denominator by 5. Also, velocity and speed are measured in N/s.

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s