Instruction

1

To determine the strength of a punch or otherwise any object, you need to know the following values: mass of the striking object, the time of contact, velocity of the striking object. The greater the speed at which a fist or other object was moving before the collision, the greater its mass and the shorter the time of contact with the obstacle which he encountered, and the greater will be the average value of the force with which the object strikes.

2

According to Newton's second law, the formula for determining the force of impact will look like the following: F = m (v1 – v2) / (t1 – t2), where m is the mass of the striking object, v1 and v2 is the speed at the beginning of the strike and after it, and t1 and t2 is the time that was spent in contact. The formula shows that the more time an impact takes, the weaker he gets. This is why boxers in training and competition wear soft gloves. They prolong the time of contact with the enemy and thereby soften the blow. As it can be seen that the force of impact greatly affects the speed. Than faster flying fist, the stronger the impact. Therefore, athletes not only build muscle mass, but learn to move fast.

3

If we are talking about vertical impact, i.e. the impact force of falling object with some height (remember the Newton and the Apple), to determine the strength you need to know the height that a flying body, the acceleration of free fall (it is equal to about 10 m/S2) and its mass. That is an Apple with a mass of approximately 200 grams, flying three meters and with the speed of about 8m/s, in contact with the ground within 4 milliseconds. The impact force is approximately 500 N. This is a fairly large size, but given that the contact was very short, the damage such power can not deal.

4

As for any impact right - the more time, the less the force of impact - while travelling in car use the seat belts and airbags. They delay the time of impact, and therefore soften its effect. Therefore, in the event of an accident they can save your life.

# Advice 2 : How to determine the force of impact

It often happens that it is necessary to measure the force of impact of the athlete in training for the establishment of any record or report to the coach. There are three methods of determining this value.

You will need

- Target;
- - the accelerometer.

Instruction

1

Use the law of conservation of potential and kinetic energy. We need it to measure the force of impact at the target. First fix the suspension on any target with a mass "m". Produce the impact and measure the value of deviation "h". This can be done using the notches on the beam, on which to fasten the makiwara. The force of the blow will be equal to the value of the formula "mgh", where g is the acceleration of free fall. By this method you can measure the impact energy accurately. Also, this method is very effective for setting for setting all kinds of records. And there, as a rule, the makiwara has an electronic sensor for even more precision.

2

Apply the device with the Doppler effect. In this case, the target is to be secured in the same way as in the previous step. The force of the impact here will be equal to the speed of the target, which propagates the ultrasound. When properly selected approach, the calibration is not required.

3

Measure the energy (force) of impact with precision triaxial or biaxial integral accelerometers. The results are in this case sufficiently accurate. The main advantage of this method is that you can strike in any direction, with the exception of strikes from the top. Although you can simply change the design and measure the strength of such impacts too.

4

Use as a measure of the force of impact of integrated accelerometers with digital output. Their advantage is that they are more sensitive and you will not need additional calibration. If the accelerometer analog output, then you need to use also the value of gravitational acceleration "g" for more accurate data of the force of the blow. The proposed measurement method solves the problem of certainty about the impact energy of the athlete. All this can help in the assessment of physical readiness of the athlete at the moment.

# Advice 3 : How to calculate impact force

Many beginners interested in the question: how to determine the impact force of a boxer, for example, a speed bag? The force of the blow, like any other force subject to physical laws and depends on several variables.

Instruction

1

To determine the strength of a punch or otherwise any object, you need to know the following values: mass of the striking object, the time of contact, velocity of the striking object. The greater the speed at which a fist or other object was moving before the collision, the greater its mass and the shorter the time of contact with the obstacle which he encountered, and the greater will be the average value of the force with which the object strikes.

2

According to Newton's second law, the formula for determining the force of impact will look like the following: F = m (v1 – v2) / (t1 – t2), where m is the mass of the striking object, v1 and v2 is the speed at the beginning of the strike and after it, and t1 and t2 is the time that was spent in contact. The formula shows that the more time an impact takes, the weaker he gets. This is why boxers in training and competition wear soft gloves. They prolong the time of contact with the enemy and thereby soften the blow. As it can be seen that the force of impact greatly affects the speed. Than faster flying fist, the stronger the impact. Therefore, athletes not only build muscle mass, but learn to move fast.

3

If we are talking about vertical impact, i.e. the impact force of falling object with some height (remember the Newton and the Apple), to determine the strength you need to know the height that a flying body, the acceleration of free fall (it is equal to about 10 m/S2) and its mass. That is an Apple with a mass of approximately 200 grams, flying three meters and with the speed of about 8m/s, in contact with the ground within 4 milliseconds. The impact force is approximately 500 N. This is a fairly large size, but given that the contact was very short, the damage such power can not deal.

4

As for any impact right - the more time, the less the force of impact - while travelling in car use the seat belts and airbags. They delay the time of impact, and therefore soften its effect. Therefore, in the event of an accident they can save your life.

# Advice 4 : How to determine the average power

Middle power is a conditional value. In cases where the force acting on the body, changing with time or action force is very small, then to determine the magnitude of the force in each moment of time is not possible. Therefore, in these cases, taking the assumption that over time the body operated constant force is equal to the average, and I expect that it's Fср.

You will need

- the ability to integrate

Instruction

1

Let the body under the action of a certain force F has changed its velocity from V1 to V2 in a short period of time Δt. The acceleration of the body is equal to a=(V2-V1)/Δt, where a and V1 and V2 are vector quantities.

2

Substitute this expression into the formula for Newton's second law: F=ma=m(V2-V1)/Δt=(mV2-mV1)/Δt, not forgetting that the force F is also a vector quantity.

3

Write down the resulting formula in a slightly different form: FΔt=mΔV =Δp. Vector quantity FΔt, is the product of force at the time of its impact is called the impulse force and measured in Newtons multiplied by the second (N•s). And the product of mass and velocity p=mV – momentum of the body or body movement. This vector quantity measured in kilograms multiplied by meter per second (kg•m/s).

4

Thus Newton's second law can be formulated differently: the impulse of the force acting on a body is equal to change of momentum: FΔt=Δp.

5

If the impact force was very small, for example, during impact, the average

**force**find: Fср=Δp/Δt=m(V2-V1)/Δt.Example: a Ball with a mass of 0.26 kg, flying at a speed of 10m/s. After hitting a player, the ball speed increased to 20 m/s Time of impact is 0.005 s. the Average force the hand of the player on the ball is equal in this case Fср=0,26•(20-10)/0.005=520Н.6

If the force acting on a body is not constant, but changes with time according to the law F(t), by integrating the function F(t) at time t in the interval from 0 to T, find the change of momentum of the body: DP=F(t)dt.

7

And the formula Fср=dp/dt, determine the value of the average power.Example: a Force changing with time according to a linear law F=30t+2. Find the average impact force for 5s. First compute the momentum p=∫(30t+2)dt=15t2+2t , then the average force: Fср=(15t2+2t)/t=15t+2=15•5+2=77Н

Note

Force is a vector quantity. If the result of the calculation value Fср turned out negative, it means that the force vector is directed in the direction opposite to the direction of the coordinate axis.

Useful advice

Don't forget when solving problems to translate everything used in formulas values in SI. Ie, mass in kilograms, speed in meters divided by the second, and force in Newtons.