What is the formula for determining the force of impact in a physics problem?

In summary, the force of the impact can be determined by finding the average force during the impact, which is equal to the mass multiplied by the average acceleration. The speed changes by an amount v in time t, so the average acceleration can be calculated. However, if you do not know how to calculate the average acceleration, then you may not be able to solve the problem.
  • #1
pantufino
5
1
So this is my first time posting, but I´ll do my best to be clear (be advised, I have translated the names of the variables from portuguese to inglish so sorry if it is confusing)
Today I was asked to solve a physics problem in class, which I had never solved anything else like it before and I was never really good at physics but whatever. the problem is as it follows:

we have a rock with a with of 600g, which was thrown into a watermelon. The impact lasted for 0,01 sec. and the rock hit the watermelon at a speed of 15m/sec.
(now this is where it gets fun)
with this data you must determine the force of the impact.

After asking for the help of the teacher she told me to do this:
so we have the delta symbol and a "t" = 0,01sec. (wich I believe it is time diference or so)
the initial velocity is = 15m/sec.
the vinal velocity is = 0m/sec.
the mass is = 600g.
the resulting force (Rf / (Fr in portuguese) formula is is Fr = (mass) x (acceleration) or Fr = m.a
wich she told me to begin the problem with that formula, myself, not being a person of physics, failed to do so.
Initialy, I started by calculating the preassure, which was impossible because I didn't knew the area of impact neither the force.
She has refused to help to solve it, and I have zero Idea how to do so. I anyone understood what the problem is ans is willing to lend a hand, it would be great.
thank you.
 
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  • #2
pantufino said:
So this is my first time posting, but I´ll do my best to be clear (be advised, I have translated the names of the variables from portuguese to inglish so sorry if it is confusing)
Today I was asked to solve a physics problem in class, which I had never solved anything else like it before and I was never really good at physics but whatever. the problem is as it follows:

we have a rock with a with of 600g, which was thrown into a watermelon. The impact lasted for 0,01 sec. and the rock hit the watermelon at a speed of 15m/sec.
(now this is where it gets fun)
with this data you must determine the force of the impact.

After asking for the help of the teacher she told me to do this:
so we have the delta symbol and a "t" = 0,01sec. (wich I believe it is time diference or so)
the initial velocity is = 15m/sec.
the vinal velocity is = 0m/sec.
the mass is = 600g.
the resulting force (Rf / (Fr in portuguese) formula is is Fr = (mass) x (acceleration) or Fr = m.a
wich she told me to begin the problem with that formula, myself, not being a person of physics, failed to do so.
Initialy, I started by calculating the preassure, which was impossible because I didn't knew the area of impact neither the force.
She has refused to help to solve it, and I have zero Idea how to do so. I anyone understood what the problem is ans is willing to lend a hand, it would be great.
thank you.
First, to be clear, the force will not be constant, but you can find the average force during the impact.
The average force is the mass multiplied by the average acceleration.
If the speed changes by an amount v in time t, do you know how to calculate the average acceleration?
 
  • #3
haruspex said:
First, to be clear, the force will not be constant, but you can find the average force during the impact.
The average force is the mass multiplied by the average acceleration.
If the speed changes by an amount v in time t, do you know how to calculate the average acceleration?
well, no...last term we studied movement, acceleration and so on. I passed only because I was lucky, I understand barely of any of it (even though I try really hard) half of the formulas are not provided to us, we just have to figure it out, which reduces kill productivity, learning and interest ( I speak for myself).
to sum it up, I know nothing.
this was provided by a friend, which I imagine is the acceleration, even if I do the math, I don't know how to move foward.
thanks
 

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  • #4
pantufino said:
well, no...last term we studied movement, acceleration and so on. I passed only because I was lucky, I understand barely of any of it (even though I try really hard) half of the formulas are not provided to us, we just have to figure it out, which reduces kill productivity, learning and interest ( I speak for myself).
to sum it up, I know nothing.
this was provided by a friend, which I imagine is the acceleration, even if I do the math, I don't know how to move foward.
thanks
That is the right equation. What is stopping you from applying it? It requires three inputs: an initial speed, a final speed and a time. You are given all of these.
 
  • #5
haruspex said:
That is the right equation. What is stopping you from applying it? It requires three inputs: an initial speed, a final speed and a time. You are given all of these.
well, after completing this we get the accelaration, but it is asked us to get the intensity of impact/ force. after that my brain blocks. You can get an idea how much I understand of this.
 
  • #6
pantufino said:
we get the accelaration
What did you get?
pantufino said:
asked us to get the intensity of impact/ force
I told you how to find the average force from the average acceleration in post #2.
 
  • #7
haruspex said:
What did you get?

I told you how to find the average force from the average acceleration in post #2.
well, I guess you did. still don't get it. I'm going to skip this one.
thank you for your time.
 
  • #8
haruspex said:
What did you get?

I told you how to find the average force from the average acceleration in post #2.
wait, I just figured it out. Jesus it was simple and I just got it all confused. Thank you again for your time. Appreciated!
 
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  • #9
pantufino said:
well, I guess you did. still don't get it. I'm going to skip this one.
thank you for your time.
I can only suppose that you have allowed yourself to get in such a state over it that you cannot think straight.
Relax, take a deep breath...
What did I write in the second sentence in post #2?
 
  • #10
pantufino said:
wait, I just figured it out. Jesus it was simple and I just got it all confused. Thank you again for your time. Appreciated!
Well done.
 
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1. How is the force of impact calculated?

The force of impact is calculated by multiplying the mass of the object by its acceleration. This can be expressed as F = m x a, where F is the force in Newtons (N), m is the mass in kilograms (kg), and a is the acceleration in meters per second squared (m/s²).

2. What factors affect the force of impact?

The force of impact can be affected by several factors, including the mass of the object, the speed at which it is moving, and the surface area over which the force is applied. Other factors such as the stiffness of the object and the angle of impact can also impact the force of impact.

3. How can the force of impact be reduced?

There are several ways to reduce the force of impact, including increasing the duration over which the force is applied, increasing the surface area over which the force is distributed, and decreasing the speed at which the object is moving. Other methods include using materials with higher elasticity or implementing safety measures such as airbags or crumple zones in cars.

4. Can the force of impact be measured in different units?

Yes, the force of impact can be measured in different units depending on the system of measurement being used. In addition to Newtons, other common units for force include pounds (lbs), kilograms-force (kgf), and dynes (dyn).

5. How does the force of impact affect living organisms?

The force of impact can have a significant impact on living organisms, causing injuries or even death. The amount of force that an organism can withstand before sustaining injury depends on various factors such as age, size, and overall health. For example, a car accident with a force of 100 Gs (100 times the force of gravity) can be fatal for a human, while a mouse can withstand a force of 1500 Gs without injury.

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