PHYSICS
posted by WASEEM .
A CAR IS MOVING INITIALLY AT A SPEED OF 50MI/H WEIGHTING 3000LB IS BROUGT TO A STOP IN A DISTANCE OF 200FT FIND THE BRAKING FORCE.AND FIND TIME REQUIRED TO STOP ASSUMING THE SAME BRAKING FORCE..AND FIND THE DISTANCE AND TIME REQUIRED TO STOP IF THE CAR WERE GOING 25MI/H INITIALLY?

Vo = 50mi/h = 22.22 m/s.
Wt. = 3000Lbs = 1362 kg.
d = 200Ft = 60.61 m.
a = Vo^2/2d = (22.22^2)/121.2 =
4.07 m/s.
Fb = M*a = 1362 * (4.07) = 5543
N. = Braking force.
V = Vo + a*t = 0.
t = Vo/a = 22.22/4.07 = 5.45 s. = Time required to stop. 
m=1362kg,v=22.22m/s,d=61m;
we know that a moving object has a kinetic energy=1/2mv^2.So the braking action would be the negative of the work done against Kinetic energy,
W(braking)=K.E i.e 0.5*1362*22.2*22.2,
we get,W=335624.04.
now,F=W/stopping dist.
i.e F=335624.04/61
This would be 5542.95 approx
and for time you can use impulse equation,F*t=p;so t=30263.64/5543=5.45s..
for the seconf just replace the value of v;
Respond to this Question
Similar Questions

Science
A car weights 1.30 X 10^4 N is initially moving at a speed of 40km/h when the brakes are applied and the car is brought to a stop in 15m. Assuming that the force that srops the car is constant. find a)magnitude of the force b)time … 
physics
A car that weighs 1.5 × 10^4 N is initially moving at a speed of 43 km/h when the brakes are applied and the car is brought to a stop in 16 m. Assuming that the force that stops the car is constant, find (a) the magnitude of that … 
physics
A car that weighs 15,000 N is initially moving at 60 km/hr when the brakes are applied. The car is brought to a stop in 30 m. Assuming the force applied by the brakes is constant, determine the magnitude of the braking force. 
college math
Braking distance The braking distance y in feetthat it takes for a car to stop on wet ,level pavement can be estimated by y = 1/9 x^2, where the x is the speed of the car in miles per hour Find the speed associated with with each braking … 
Maths
The braking distance of a car is directly proportional to te square of it's speed. When the speed is p metres per second, the braking distance is 6m. When the speed is increased by 300%, find (a) an expression for speed of the car … 
Physics
The driver of a car on a horizontal road makes an emergency stop by applying the brakes so that all four wheels lock and skid along the road. The coefficient of kinetic friction between tires and road is 0.39. The separation between … 
Physics
A car moving initially at a speed of 80 km/h and weighing 13,000 N is brought to a stop ina distance of 61 m. Find(a) the braking force and (b) the time required to stop. Assuming the same braking force, find (c) the distance and (d) … 
Physics
You are driving down the highway late one night at 20 m/s when a deer steps onto the road 35 m in front of you. Your reaction time before stepping on the brakes is 0.50 s , and the maximum deceleration of your car is 10 m/s2 . How … 
physics
A 600 kg car is moving on a level road at 30 m/s. How large of a braking force is needed to stop it in a distance of 75m? 
Physics
A driver in a car, originally moving at 13.1 m/s, applies the brakes until the car comes to a stop. The car moves a distance of 34.1 m while braking. How much time did it take for the car to stop?