00:01
In this question, there's a truck on a straight route that starts from wrestling accelerates at 2 meter per second until it reaches the speed of 20 meter per second.
00:08
Now truck travels for 20 seconds at constant speed until the brakes are applied and stopping the truck in uniform and an additional 5 seconds.
00:15
So how long is the truck in motion? so let's say it starts from a goes to b while accelerating.
00:22
From b to c it is in constant speed at 20 meter per second and from c to d it travels for 20 seconds it's for 20 seconds one second this is actually 20 second where 20 second it moves at a constant speed so this is 20 seconds and it stops in another five seconds and it starts from res so this is zero and this is two meter per second square and it reaches a speed of 20 meter per second so we have to find the total time how long is the truck in motion so we need to find the total time so we need to find this t1 so we can use the first equation of motion this is part a which is v is equal to v0 plus a t so v is 20 v0 0 is 2 1 time is something which we need to find so clearly t 1 is nothing but 20 over 2 which is 10 so the total time is the total time of motion total time is nothing but 10 plus 20 plus 5 which is 35 seconds and if we talk about part b how long is the truck part b what is the average velocity of the truck for the motion described so the average velocity is the total distance over total time total time we know let's talk about the total distance so for the total distance we have to find the distance d1 then distance d2 and then distance d3 okay so i think we can use the second equation of motion to find d1 so b1 is going to be equal to v0 t plus half a t squared so this is nothing about v0 is 0 this is that's the initial velocity half 2 and t1 squared t1 is 100 10 so that's 10 square you on over here so this comes out as 100 d2 is constant speed so that's just speed times time so that's 20 times 20 which is 400 both in meters and d3 is we can use this third equation of motion which says that which says that v square is equal to v0 square plus 2 a s are we given all right we are not given time over here so can we use the we can use the second equation of motion in fact once again so d3 is going to be equal to initial speed which is 20 times time which is 5 plus but not plus plus plus half a t square where t is again 5 but we don't know a.
03:06
So if we don't know the acceleration, we are going to use the third equation of motion first to determine the acceleration.
03:13
So for this part, we know that v squared is equal to v0 square plus 2 as.
03:21
So i'm sorry, we are going to use the first equation of motion, which is v.
03:25
Is equal to v0 plus a t.
03:27
So initial is 20...