MEchanics M1 (Velovity time graphs)
posted by Tony .
A dragonfly, at rest on a bullrush, decides to fly to a second bullrush 18 m away. It accelerates uniformly to a speed of. 5 m s1, then immediately decelerates uniformly to rest on the second bulrish. Howlong the journey took?

The average speed is 2.5 m/s, both accelerating and decelerating. So it is 2.5 m/s for the whole trip.
The elapsed time is the distance divided by the average speed, or 18/2.5 = 7.2 seconds
Respond to this Question
Similar Questions

applied maths
A tram starts from rest atone station and comes to a stop one minute later at the next. It accelerates uniformly at 2m/s2 until it reaches a speed of 20m/s. It travels at this constant speed for a certain time until it decelerates … 
Physics
1. A car starts from rest and accelerates uniformly at 3.0 m/s2. A second car starts from rest 6.0 s later at the same point and accelerates uniformly at 5.0 m/s2. How long does it take the second car to overtake the first car? 
physics
A car starting from rest accelerates uniformly are attaing a speed of 80m/s in 30s it maintains this stedy speed for another 30s. It then slow down uniformly until it comes to rest in the next 40s 
math(mechanics 1)
a car traveling on a straight road accelerates uniformly at a meter per second square from its initial speed of 20 meter per second until it reaches a speed of 30 meter per second. the car travels at this speed for 600 meter and then … 
math
The diagram below shows the speed time graph for a train travelling between two stations. The train starts from rest and accelerates uniformly for 150 seconds. It then travels at a constant speed for 300 seconds and finally decelerates … 
mechanical science
10. A car is moving in a straight line starts from rest, accelerates uniformly at 12 m/s2 for the first 5s, then travels at uniform speed for the next 2s and finally decelerates uniformly at 4 m/s2 for the next 5s. Draw the accelerationtime … 
Help! Calculus
An elevator in a high rise building accelerates and decelerates at the rate of 1 foot per second squared. Its maximum speed is 8 feet per second. It starts from rest, accelerates to its maximum speed and stays at that maximum speed … 
calculus HELP!
An elevator in a high rise building accelerates and decelerates at the rate of 1 foot per second squared. Its maximum speed is 8 feet per second. It starts from rest, accelerates to its maximum speed and stays at that maximum speed … 
science
An elevator in a high rise building accelerates and decelerates at the rate of 1 foot per second squared. Its maximum speed is 8 feet per second. It starts from rest, accelerates to its maximum speed and stays at that maximum speed … 
Physics
A vehicle of mass 1200 kg accelerates uniformly from rest to a velocity of 15 m/s in 5 seconds. It continues at this velocity for 15 seconds before decelerating uniformly at a rate of 5m/s2 to rest. Determine the following: (i)The …