Find velocity using Force -time graph

The area of the second bit (100 ms - 150 ms): [ 10 N * 50 x 10^-3 sec / 200 x 10^-3 kg -- factors of 10^-3 cancel = 2.5 m/s] The velocity at 150 ms is the sum of these two areas: [ 8.75 m/s + 2.5 m/s = 11.25 m/s ] In summary, the variation of the force F with time t on a body of mass 200g is shown in the graph. The velocity of the body at t=75ms is given as 15m/s. To find the velocity at t=150ms, we calculate the area
  • #1
jake jungle
12
0

Homework Statement


upload_2015-2-25_0-32-46.png

The variation of the force F with the time t acting on a body of mass 200g is as shown in the graph below
Given that the velocity of the body at t=75ms is 15m/s . What is the velocity of the body at t=150ms
A.15m/s
B.30m/s
C.35m/s
D.39m/s

Homework Equations


F = m Δv/Δt

The Attempt at a Solution


so i calculate the area of ABCDE , and it equal the change of momentum from 75ms to 150ms
the i calculate the momentum of the body in t = 75ms using v = 15m/s and mass of 200g
=> momentum of the body in t = 150ms => v
however i don't get any answer in the choices . please tell me where i was wrong
 

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  • #2
It will be easier to know where you go wrong if you provide your actual computations rather than describing them in words. The general idea is correct.
 
  • #3
v = v_0 + integral [dt*F/m]

Units matter. The area of the first bit (75 ms - 100 ms): [ 70 N * 25 x 10^-3 sec / 200 x 10^-3 kg -- factors of 10^-3 cancel = 8.75 m/s]
 

Related to Find velocity using Force -time graph

1. How do I find velocity using a Force-time graph?

To find velocity using a Force-time graph, you need to calculate the area under the curve of the graph. This can be done by dividing the total area into smaller shapes, such as rectangles or triangles, and calculating the area of each shape. Then, add up all the areas to find the total area under the curve.

2. What units should I use for velocity and force on the graph?

Velocity is typically measured in meters per second (m/s) and force is measured in Newtons (N). It is important to use consistent units when calculating the area under the curve of the graph to ensure accurate results.

3. Can I find velocity at a specific point on the graph?

Yes, you can find the velocity at a specific point on the graph by drawing a tangent line at that point and calculating its slope. The slope of the tangent line will represent the instantaneous velocity at that point.

4. How does the shape of the Force-time graph affect the velocity calculation?

The shape of the Force-time graph can affect the velocity calculation because it determines the type of area calculation that needs to be done. For example, a curved graph may require the use of calculus to find the area under the curve.

5. What other factors should I consider when using a Force-time graph to find velocity?

When using a Force-time graph to find velocity, it is important to consider the mass of the object and any other external forces acting on it. These factors can affect the acceleration of the object and therefore the velocity calculation. It is also important to have accurate and precise measurements to ensure the reliability of the results.

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