Q1.find out distance travelled by the block in 10s for the given situation
Answers
Explanation:
Given, initial velocity (u) = 10m/s
acceleration (a) = - 2m/s²
To find : Distance traveled in 10 seconds.
Finding final velocity for the given time.
1st Equation of motion
v = u + atv=u+at
Final velocity after 10 seconds
v = 10 + (-2)(10)
v = - 10 m/s
This shows the body is going to move in the opposite direction. So Distance ≠ Displacement and we can't use the second equation of motion directly.
From first equation of motion, Velocity after t seconds can be given by,
v = 10 - 2t
Finding the time at which velocity becomes 0 ( If velocity becomes zero for a body on a straight path, we may consider it to be changing direction)
So,
0 = 10 - 2t
10 = 2t
t = 5 seconds.
Therefore, The body travels for 5 seconds in the current direction, later it changes it's direction of motion.
Distance traveled in 10 seconds
= Distance traveled in the first 5 seconds + Distance traveled in the second 5 seconds.
For the first 5 seconds
u = 10m/s
a = - 2m/s²
t = 5 s
S = ut + ½at²
S = 10(5) + 1/2 ( - 2)(5²)
S = 50 - 25
S = 25 m.
For the last 5 seconds,
u = 0 m/s
a = - 2 m/s²
t = 5s
S = ut + 1/2at²
S = 0(5) + 1/2 ( - 2)(5)²
S = - 25m.
The body travels this distance in the opposite direction of initial motion.
Therefore, The total distance traveled by the body in 10 seconds is 25 + 25 = 50m.