can someone please answer this simple physics question for me?

Question

SITUATION: A 1300-kg car travels at 22 m/s and then quickly stops in 3.6 s to avoid an obstacle.

QUESTIONS:
a) What is the initial speed of the car in mph?
b) What is the initial kinetic energy of the car in kilojoules (kJ)?
c) What is the initial momentum of the car? (In kg*m/s)
d) What is the magnitude of the impulse necessary to stop the car? (in kg*m/s)
e) What is the magnitude of the average force in kiloNewtons (kN) that stopped the car?
f) What is the magnitude of the average acceleration that stopped the car? (m/s^2)


thanks..

Answer 1

a) 22 m/s
b) 1/2 mv^2 = 1/2 (1300 kg ) 22^2 = 314600 J
= 315 KJ
c) 1300 kg * 22 m/s = 28600 kg m/s
d) 28600 kg m/s

Ooops gotta go!

Answer 2

a. Your first question is nothing more than a unit conversion question. There are 3600 seconds in one hour and 1609.3 m in one mile.

b. KE = 1/2 m v^2 plug in initial values.

c. p = m v plug in initial values.

d. Impulse is the total change in momentum. p(final) - p(initial) = I

e. Force is equal to Impulse per unit of time. F = I / t

f. Find using Newton's second law: F = m a, so a = F / m

Answer 3

Your teacher uses this site too and considers this cheating... Close the laptop and open your text book!