Qualification > Sciences

another physics doubts

(1/2) > >>

helllife:
question is.......

On a foggy day, two car drivers spot each other, when they are just 80m apart. They are travelling at 72km/h and 60km/h respectively. Both of them simultaneously apply breaks when retard the cars at 5m/s2. Determine whether they avert the collision or not?

what would the answer and can u please show the working of how u got the answer?

vaan:

--- Quote from: helllife on November 12, 2009, 05:59:11 pm ---question is.......

On a foggy day, two car drivers spot each other, when they are just 80m apart. They are travelling at 72km/h and 60km/h respectively. Both of them simultaneously apply breaks when retard the cars at 5m/s2. Determine whether they avert the collision or not?

what would the answer and can u please show the working of how u got the answer?

--- End quote ---

when de break is applied...de 1st car....it takes goes...72/5 = 14.4m
for de second car....after breaks r applied it moves...60/5 = 12m
dey already have a distance of 80m...n even after de breaks r applied de distance increases 14.2 - 12 = 2.2m
so de total distance between cars now is 80 + 2.4 = 82.4m...
hence dey don have a crush.....

helllife:
do u mean (70/5) as (a/v)? isnt it time?? how did u find in distance?

astarmathsandphysics:
72km/h=72000/3600=20m/s
and 60km/h=16.67m/s

v^2=u^+2as for each car
0=20^2+2*-5*s so s=40m for car 1
0=16.67^+2*-5*s so s=27.78 for car 2. The cars close by 67.78 so do not collide.

helllife:
thanks astar!!!  :)
i have another question....on projectile.....

A fighter plane flying horizontally at an altitude of 1.5km with a speed of 720km/h passes directly overhead an anti-aircraft gun. At what angle from the vertical should the gun be fired for the shell with muzzle speed 60m/s to hit the plane?

the answe is 19.47', can u show the workings??

Navigation

[0] Message Index

[#] Next page