Calculating Time for 1000kg Boat to Slow from 90km/h to 45km/h

  • Thread starter Fallinleave
  • Start date
  • Tags
    Friction
In summary, The boat, weighing 1000kg, is initially traveling at 90km/h when its engine is shut off. The frictional force between the boat and water is given by fk=70v, where v is the speed in meters per second and fk is in Newtons. The question asks for the time required for the boat to slow down to 45km/h without mentioning acceleration. To find the time, you would need to use Newton's second law and solve the differential equation for velocity v and acceleration dv/dt.
  • #1
Fallinleave
9
0
A 1000kg boat is traveling at 90km/h when its engine is shut off. The magnitude of frictional force fk between boat and water is proportional to the speed v of the boar: fk=70v, where v is in meters per second and fk is in Newtons. find the time required for the boat to slow to 45km/h.

The question does not ask for acceleration, so do I need to find the acceleration before finding the time?

In addition, Does anyone knows how to use a math template for posting this type of question?

Thanks,
 
Physics news on Phys.org
  • #2
Any thought on it would be fine, thanks.
 
  • #3
Use Newton's second law to get the relation between velocity v and acceleration, dv/dt. Solve the differential equation.

ehild
 

1. How do you calculate the time it takes for a 1000kg boat to slow from 90km/h to 45km/h?

To calculate the time it takes for a 1000kg boat to slow from 90km/h to 45km/h, we need to use the equation: time = (final velocity - initial velocity) / acceleration. In this case, the acceleration will be negative as the boat is slowing down. Therefore, the equation becomes: time = (45km/h - 90km/h) / (-9.8m/s^2). This gives us a time of approximately 4.6 seconds.

2. What is the acceleration of the 1000kg boat as it slows down from 90km/h to 45km/h?

The acceleration of the 1000kg boat can be calculated using the equation: acceleration = (final velocity - initial velocity) / time. In this case, the initial velocity is 90km/h, the final velocity is 45km/h, and the time is 4.6 seconds. Plugging these values into the equation gives us an acceleration of approximately -9.8m/s^2.

3. How does the mass of the boat affect the time it takes to slow down?

The mass of the boat does not affect the time it takes to slow down. The time is only dependent on the initial and final velocities and the acceleration. However, the acceleration of the boat will be affected by its mass. A heavier boat will require more force to slow down, resulting in a slower acceleration and a longer time to slow down.

4. Is the time calculation affected by external factors such as wind or water currents?

The time calculation is not affected by external factors such as wind or water currents. This calculation assumes that the boat is slowing down in a controlled environment with no external forces acting on it. In reality, external factors may affect the boat's speed and acceleration, and the time to slow down may vary.

5. Can this time calculation be applied to other objects besides a 1000kg boat?

Yes, this time calculation can be applied to any object as long as the initial and final velocities and the acceleration are known. However, the units of measurement may need to be converted to ensure consistency. Additionally, the actual time it takes for an object to slow down may vary depending on external factors and the object's specific characteristics.

Similar threads

Friction Force and Decelerating Boat
    • Introductory Physics Homework Help
Replies
3
Views
1K
Force and motion in Newton's laws
    • Introductory Physics Homework Help
Replies
2
Views
1K
Boats in a triangle colliding after some time
    • Introductory Physics Homework Help
Replies
2
Views
963
Solving Boat's Friction Force and Speed
    • Introductory Physics Homework Help
Replies
9
Views
1K
Finding Time for Boat to Slow Down with Velocity Dependent Forces
    • Introductory Physics Homework Help
Replies
2
Views
2K
Boat Friction Physics Problem: Finding the Time to Slow from 90km/h to 45km/h
    • Introductory Physics Homework Help
Replies
21
Views
3K
Friction problem from Halliday and Resnick
    • Introductory Physics Homework Help
Replies
4
Views
4K
Help Solve Differentiation Problem to Slow Boat Speed to 45 km/h
    • Introductory Physics Homework Help
Replies
2
Views
1K
Friction & movement in a system with body above moving body
    • Introductory Physics Homework Help
Replies
9
Views
2K
Summing forces: finding acceleration and F_n
    • Introductory Physics Homework Help
Replies
5
Views
28K

Hot Threads

Recent Insights

Back
Top