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What the total distance if a body acquires velocity of 90 meter per second in 25 minutes and move with the same velocity for 2 hours and apply brakes then the body come to rest in 25 minutes?
Wiki User
∙ 12y ago
-- You haven't said what the object's speed was at the beginning of the
25 minutes. We'll assume that it started from rest at the beginning of
this whole exercise.
-- We're also going to work exclusively with the object's speed. Since you
haven't said anything about the direction in which it moves at any moment,
we have no way to work with velocity. Fortunately, it doesn't matter.
The motion occurs in three distinct periods, which we'll consider separately:
Period I:
Zero to 90 m/s in 25 minutes.
Average speed = 45 m/s.
Distance = (average speed) x (time) = (45 meter/sec) x (60 sec/min) x (25 min) = 67,500 meters.
Period II:
(90 meters/sec) x (3,600 sec/hour) x (2 hours) = 648,000 meters
Period III:
A perfect time-reversal of Period-I ... like running the video backwards.
Same distance as Period-I = 67,500 meters.
Total distance = (67,500) + (648,000) + (67,500) = 783 kilometers.
======================================================
Period-I
S = vit + 1/2 a t2
vi = 0
Acceleration = [ (90 meter/sec) x (1/25 min) ] x (1 min/60 sec) = 0.06 meter/sec2
t = 25 minutes = 1,500 sec
1/2 a t2 = 1/2 (0.06) (1,500)2 = 67,500 m
Period-II
S = v t = (90 meters/sec) x (2 hours) x (3,600 sec/hour) = 648,000 m
Period-III
Either recognize that Period-III is exactly the same as Period-I in reverse,
or else
you can use
S = vit + 1/2 a t2
vi = 90 meters/sec
t = 25 min = 1,500 sec
Acceleration = -0.06 meter/sec2
vit + 1/2 a t2 = (90)(1,500) + 1/2(-0.06)(1,500)2 = (135,000) + (-67,500) = 67,500 m
Wiki User
∙ 12y ago
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If only external force can change the velocity of a body how can the internal force of the brakes bring a car to rest?
It is not the force of the brakes that is stopping the car but rather external force of friction between tires and the road. Notice that no matter what the force at the brakes is, the car won't stop if there is no friction there(ie. the road is slippery). This is an excellent question. Consider the NASA space shuttle. It has brakes, yet the brakes work only on the ground - only while the shuttle is landing. Why? In space, the brakes have nothing to react against. So, as the questioner suspects, the internal forces of the brakes alone are not sufficient to change the velocity of the space shuttle. But once the shuttle lands, and is rolling down the runway, applying the brakes creates friction between the wheels and the runway. And it is the external force of the runway pushing back against the braking wheels that causes the shuttle to slow down.
How many feet will it take you to stop your car if you going 60 mph?
Without knowing either the rate of negative acceleration or the time it takes for the car to stop, this question cannot be answered. There are three kinematic equations that could be used to answer this question. They are as follows:d = (v_i)(t) + (1/2)(a)(t^2)d = (v_i + v_f)/2 x tV_f^2 = v_i^2 + 2ad, solve for dIn these equations, d is displacement, a is acceleration, t is time, v_i is initial velocity, and v_f is final velocity.
Under favorable circumstances including reaction time a motor vehicle with good brakes going 50 miles per hour can be stopped within how many feet?
The typical BREAKING distance from 50mph is 38meters, but the overall stopping distance is 53meters (overall stopping distance is made up of thinking distance, which is 15meters in this case, + breaking distance)
How bits can move rock long distance?
They can be moved by the rain coming down and landing on the rock so the rock brakes and crumbles off.Also it can be caused by the wind blowing on the rock and bits can fall off the rocks.
How do you explain a car requires brakes in order to stop with law of motion?
try stopping a car without brakes!
What the total distance of a body acquires the velocity of 90 km per hour in 25 minutes it then continuous for 2 hours when brakes applied it comes into rest in 25 minutes?
255 km
Why are larger brakes prefered over smaller brakes in vehicles?
Larger brakes = shorter stopping distance.
Can hot brakes cause a tire fire?
If brakes are sticking and you drive for a long distance, then yes
What is braking distance composed of?
Braking distance is usually measured by how fast you can stop at 60mph, 60-0, the make of a car is the factor of the stopping distance, each car varies. Your car can have disc brakes or drum brakes or both. Disc brakes are more effective than drum brakes. But braking distance is usually showed by how many feet it takes to stop from 60mph
What is braking distance?
The distance a vehicle will travel between putting on the brakes and coming to a stop.
Can a moving body have velocity and acceleration in opposite directions explain with in example?
Of course. A car with brakes applied and slowing down has forward velocity and rearward acceleration.
How do you decrease velocity of a moving car?
You increase the frictional force by applying the brakes.
What should you do if your brakes become wet?
While driving, apply the brakes gently for a short distance, as you maintain your speed.
After a short distance 1990 Jaguar XJS brakes slowly apply until the wheels are solidly locked The brake pedal is solid After 30 minutes they are fully released again What is the problem?
overheating
Do drum brakes work better than disk brakes?
No, they are inferior to disc brakes. Drum brakes were used from the beginning of the auto up until the late 60s. Drum brakes are more prone to overheating than disc brakes. Disc brakes also shed water much better than drum brakes which improves stopping distance in wet conditions. Disc brakes apply pressure more evenly than drum brakes thus improving stopping distance. Disc brakes are superior in every way.
What can increase braking distance?
Poor brakes and bald tyres
Can i drive with no rear brakes?
No. Your stopping distance will almost double.
