# At what speed does the food enter the stomach

• frozen7
In summary, the morsel of food with a mass of 4.2g is injected into the esophagus with an initial speed of 2.5cm/s. On the way down to the stomach, the walls of the esophagus exert an upward resistive force of 0.0027 N on the morsel. If the esophagus is 20cm long, with what speed does the morsel of food enter the stomach?
frozen7
A morsel of food with a mass of 4.2g is injected into the esophagus with an initial speed of 2.5cm/s. On the way down to the stomach, the walls of the esophagus exert an upward resistive force of 0.0027 N on the morsel. Ifthe esophagus is 20cm long, with what speed does the morsel of food enter the stomach?

I solve it by :

Wf = 1/2 m (v^2 - u^2) and I got the wrong answer.

Can anyone tell me what`s wrong with it?

I feel very blur with enerygy concept, especially relate with non conservative force. Can anyone summarize the important concept about energy for me?

I don't see that energy has anything to do with it.

Although you say "down" the gullet, I feel sure you are not assuming the esophagus is not straight up and down and that there is no gravitational acceleration downward!
In that case, the only force on the food is the upward force of 0.0027 N and so the acceleration is 0.0027N/0.0042 kg= 0.64 m/s2= 64.29 cm/s2.

Now use d= (1/2)at2+ v0t and v= at+ v0
with a= 64.29 dm/s2, v0= -2.5 c/s, and d= -20. Solve the first equation for t, the time the food takes to get to the stomach, then use the second equation to find v, the speed of the food at that time.

Having said all of that, I'm going to rethink what I initially said: You can use the mass and initial speed of the food to find its initial kinetic energy. That is decreased by the work the esophagus does on the food: Work= Force*distance= 0.0027 N* 0.20 m. Subtracting that from the initial kinetic energy gives the final kinetic energy of the food: you can find the speed from that.

Be sure to use consistent units! Either meters, kilograms, Newtons, and Joules or cm, grams, dynes, and ergs.

I get this equation from my textbook:

Work done by non conservative force = change in KE + change in PE

If I apply this formula in this question, why can't i find the true answer?

It appears that you are not using the CHANGE in KE and PE in your original equation. Since the food has an initial velocity and a final velocity, there need to be two terms for the velocity in the KE portion of the equation.

Start by calculating each component of your equation:
WORK: $$W_f = F*d$$

KE: $$\Delta KE = \frac{1}{2} m ({v_2}^2 - {v_1}^2)$$

PE: $$\Delta PE = m*g (h_2 - h_1)$$

You know every component except $$v_2$$

Last edited:
I got it. Thanks.

## 1. What determines the speed at which food enters the stomach?

The speed at which food enters the stomach is primarily determined by the consistency and size of the food particles. Foods that are more solid and larger in size take longer to break down and therefore enter the stomach at a slower pace.

## 2. Does the type of food affect the speed of digestion?

Yes, the type of food can have a significant impact on the speed at which it enters the stomach. Foods that are high in fat and protein take longer to digest and therefore enter the stomach more slowly compared to foods that are high in carbohydrates.

## 3. How does chewing affect the speed of food entering the stomach?

Chewing is an important step in the digestion process as it breaks down food into smaller pieces, making it easier for the stomach to digest. Properly chewing food can help it enter the stomach at a more consistent and efficient speed.

## 4. Can the speed at which food enters the stomach affect digestion?

Yes, the speed at which food enters the stomach can have an impact on digestion. If food enters the stomach too quickly, it may not be properly broken down and can lead to discomfort or indigestion. On the other hand, if food enters the stomach too slowly, it may cause bloating or constipation.

## 5. Are there any factors that can influence the speed at which food enters the stomach?

Aside from the type and consistency of food, there are a few other factors that can affect the speed of food entering the stomach. These include stress levels, physical activity, and overall digestive health. It's important to maintain a balanced diet and healthy lifestyle to promote efficient digestion.

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