(3%) Problem 31: A car moving at 9.5 m/s crashes into a tree and stops in 0.24 s
ID: 1785443 • Letter: #
Question
(3%) Problem 31: A car moving at 9.5 m/s crashes into a tree and stops in 0.24 s 50% Part (a) Calculate the magnitude of the force, in newtons, the seatbelt exerts on a passenger in the car to bring him to a halt. The mass of the passenger is 72.5 kg Grade Summary Potential Submissions 0% 100% sin0 cosO cotanO asin0 acos0 atanO acotan)sinh(0 cosh0 tanh) cotanh0 Degrees Radians tan Attempts remaining: Z (29% per attempt) detailed view 0 END DEL CLEAR Submit Hint I give up! Hints: 0% deduction per hint. Hints remaining: 1 Feedback: 0% deduction per feedback. D 50% Part (b) What would the final velocity be, in meters per second, if the car with the 725-kg passenger had collided with (and stuck to) a car that has a mass equal to and is traveling in the opposite direction and at the same speed?Explanation / Answer
Given that,
u = 9.5 m/s
t = 0.24 s
m = 72.5 kg
car finaly stops. so, v = 0
(a)
from kinematic equation,
v = u + at
0 = 9.5 + a*0.24
a = -39.58 m/s^2
Magnitude of force,
F = ma
F = 72.5*39.58
F = 2869.79 N
(b)
As given that,
m1 = m2
v2 = -v1
let, final velocity of car = v
From momentum conservation,
m1v1 + m2v2 = (m1 + m2)*v
m1v1 - m1v1 = (m1 + m2)*v
v = 0
final velocity of car is 0.
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