a train is moving at 30m/s when the brakes are applied the retardation is 2m/s (square). find the velocity after 10sec and the time taken for the tree to come to rest
vf=vo+a t
use that formula for both parts.
When rearranging a dorm room a student does 291 J of work in moving a desk 3.4 m. What was the magnitude of the applied horizontal force?
To solve this problem, we can use the equations of motion.
1. Finding the velocity after 10 seconds:
The initial velocity (u) is 30 m/s, the acceleration (a) is -2 m/s² (negative because it is a retardation), and the time (t) is 10 seconds.
The equation of motion to find the final velocity (v) is: v = u + at
Plugging in the values: v = 30 m/s + (-2 m/s²) * 10 s
v = 30 m/s - 20 m/s
v = 10 m/s
Therefore, the velocity after 10 seconds is 10 m/s.
2. Finding the time taken for the train to come to rest:
We can use another equation of motion to find the time (t₂) taken for the train to come to rest, when the final velocity (v) is 0 m/s.
The equation of motion to find the time is: v = u + at
Plugging in the values: 0 m/s = 30 m/s + (-2 m/s²) * t₂
Rearranging the equation: 2 m/s² * t₂ = 30 m/s
Dividing both sides by 2 m/s²: t₂ = 30 m/s / 2 m/s²
t₂ = 15 s
Therefore, the train will take 15 seconds to come to rest.
In summary:
- The velocity after 10 seconds is 10 m/s.
- The time taken for the train to come to rest is 15 seconds.