Physics Kinematics Question.

In summary: So the flow velocity is 6 km/hr.In summary, the flow velocity of the stream can be determined by dividing the distance traveled by the raft (6 km) by the time it took (60 minutes), resulting in a flow velocity of 6 km/hr. The velocity of the motorboat and its observer status are not relevant to this calculation.
  • #1
LHC_23
14
0

Homework Statement



A motorboat going downstream overcame a raft at a point A;
• = 60 min later it turned back and after some time passed the raft
at a distance l = 6.0 km from the point A. Find the flow velocity
assuming the duty of the engine to be constant.



Homework Equations



---------------------------------

The Attempt at a Solution



I assumed the stream velocity as v0 and the velocity of the motorboat with respect to water as v' . The motorboat reached point B while going downstream with velocity (v0 + v') and then returned with velocity (v' - v0) and passed the raft at point C . Then I assumed t to be the time for the raft to move from point A to C , during which the motorboatboat moves from A to B and then from B to C .

But after this I have no idea how to proceed .
Pls Help!
 
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  • #2
Let [tex]v_{0}[/tex] be the velocity of the stream, [tex]v[/tex] velocity of the motorboat, [tex]t_{0}[/tex] time after the motorboat changes direction (60 minutes) and [tex]L[/tex] distance form point A (6 km).

After 60 minutes, distance between boats is

[tex]d=vt_{0}.[/tex]

At that moment, motorboat is at point B. After time [tex]t[/tex] passes, the boats meet at point C. So, they travel their own distances in the same time interval [tex]t[/tex]. Therefore

[tex]d=vt_{0}=v_{0}t+(v-v_{0})t.[/tex]

And we also know

[tex]L=v_{0}(t+t_{0}).[/tex]

[tex]v_{0}[/tex] is easy to obtain from those equations.
 
  • #3
ArkaSengupta said:

Homework Statement



A motorboat going downstream overcame a raft at a point A;
• = 60 min later it turned back and after some time passed the raft
at a distance l = 6.0 km from the point A. Find the flow velocity
assuming the duty of the engine to be constant.



Homework Equations



---------------------------------

The Attempt at a Solution



I assumed the stream velocity as v0 and the velocity of the motorboat with respect to water as v' . The motorboat reached point B while going downstream with velocity (v0 + v') and then returned with velocity (v' - v0) and passed the raft at point C . Then I assumed t to be the time for the raft to move from point A to C , during which the motorboatboat moves from A to B and then from B to C .

But after this I have no idea how to proceed .
Pls Help!

But the motorboat is only an observer, otherwise irrelevant. The raft traveled 6 km in 60 minutes.
 

1. What is kinematics in physics?

Kinematics is a branch of physics that studies the motion of objects without considering the forces that cause the motion.

2. What are the three main variables in kinematics?

The three main variables in kinematics are position, velocity, and acceleration. Position describes an object's location in space, velocity describes the rate of change of position, and acceleration describes the rate of change of velocity.

3. What is the difference between speed and velocity?

Speed is a scalar quantity that describes the rate at which an object moves, while velocity is a vector quantity that describes both the speed and direction of an object's motion.

4. How is acceleration related to velocity?

Acceleration is the rate of change of velocity over time. If an object's velocity is changing, whether it is increasing or decreasing, it is said to be accelerating.

5. What is the difference between average and instantaneous velocity?

Average velocity is the total displacement of an object over a given time period, while instantaneous velocity is the velocity of an object at a specific moment in time. Average velocity takes into account the entire motion of an object, while instantaneous velocity only describes the velocity at a single point in time.

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