A body is moving with an initial velocity of 36km/hr accelerates uniformly at the rate of 4m/s for 15s. Calculate the total distance travelled in 20s and the final velocity?

To calculate the total distance traveled in 20s and the final velocity, we can follow these steps:

Step 1: Convert the initial velocity from km/hr to m/s.
Given initial velocity = 36 km/hr
1 km/hr = 1000 m/3600 s (conversion factor)
So, initial velocity = (36 * 1000) / 3600 = 10 m/s

Step 2: Use the formula for distance traveled during uniform acceleration:
Distance (d) = (initial velocity * time) + (0.5 * acceleration * time^2)

Given time = 15s and acceleration = 4 m/s^2, we can find the distance traveled in 15s.

d1 = (10 * 15) + (0.5 * 4 * 15^2)
= 150 + (0.5 * 4 * 225)
= 150 + 450
= 600 meters

Step 3: To find the final velocity, use the formula:
Final velocity (v) = initial velocity + (acceleration * time)

Given time = 15s and acceleration = 4 m/s^2, we can calculate the final velocity.

v = 10 + (4 * 15)
= 10 + 60
= 70 m/s

Step 4: Calculate the distance traveled in the remaining 5 seconds (20s - 15s).
Using the formula, d2 = initial velocity * time + 0.5 * acceleration * time^2, where time = 5s, initial velocity = 70 m/s, and acceleration = 4 m/s^2.

d2 = (70 * 5) + (0.5 * 4 * 5^2)
= 350 + (0.5 * 4 * 25)
= 350 + 50
= 400 meters

Step 5: Calculate the total distance traveled in 20s.
Total distance = d1 + d2
= 600 + 400
= 1000 meters

Therefore, the total distance traveled in 20 seconds is 1000 meters and the final velocity is 70 m/s.