a body moves in a straight line with initial velocity and uniform acceleration.find how far it travels in12s,given that it travel 246m in the 1st 6seconds,and 69m in the last 3seconds.find also the initial velocity.

User Icon for drwls drwls answered
11 years ago

V = Vo + a t

X = Vo*t + (a/2) t^2 (distance travelled at time t)
Vo is the initial velocity and a is the acceleration.

Velocity at t = 10.5 s = 69/3 = 23 m/s
Velocity at t = 3 s = 246/6 = 41 m/s
Acceleration = (23 - 41)/7.5 = -2.4 m/s^2

41 = Vo + 3a = Vo - 7.2
Vo = 48.2 m/s

Total distance travelled at t = 12 s
= 48.2*12 - 1.2*144 = 405.6 m

User Icon for Fatima Fatima answered
11 years ago

thanks alot

User Icon for Explain Bot Explain Bot answered
11 months ago

To solve this problem, we can use the kinematic equation:

distance (d) = initial velocity (u) * time (t) + (1/2) * acceleration (a) * time (t)^2

We are given specific distances for the first 6 seconds and the last 3 seconds, which can help us find the acceleration (a). Here's how we do it step by step:

Step 1: Calculate the acceleration (a):
Using the distance formula, d = ut + (1/2)at^2, for the first 6 seconds:
246 = u * 6 + (1/2) * a * 6^2
246 = 6u + 18a (equation 1)

Using the distance formula, d = ut + (1/2)at^2, for the last 3 seconds:
69 = u * 3 + (1/2) * a * 3^2
69 = 3u + 4.5a (equation 2)

Step 2: Solve the simultaneous equations:
From equation 1, we can express 6u as 246 - 18a and substitute it into equation 2:
69 = (246 - 18a) + 4.5a
69 = 246 - 18a + 4.5a
69 - 246 = -13.5a
-177 = -13.5a
a = (-177) / (-13.5) = 13.11 m/s^2 (approx.)

Step 3: Find the initial velocity (u):
Substitute the value of acceleration (a) into equation 1:
246 = 6u + 18 * 13.11
246 = 6u + 235.98
6u = 246 - 235.98
6u = 10.02
u = 10.02 / 6 = 1.67 m/s (approx.)

Step 4: Calculate the total distance traveled in 12 seconds:
Using the distance formula for the entire 12 seconds:
d = ut + (1/2)at^2
d = 1.67 * 12 + (1/2) * 13.11 * 12^2
d = 20.04 + 93.852
d = 113.892 m (approx.)

Therefore, the body travels approximately 113.892 meters in 12 seconds, and the initial velocity is approximately 1.67 m/s.