What is Impact force: Definition and 108 Discussions
In mechanics, an impact is a high force or shock applied over a short time period when two or more bodies collide. Such a force or acceleration usually has a greater effect than a lower force applied over a proportionally longer period. The effect depends critically on the relative velocity of the bodies to one another.
At normal speeds, during a perfectly inelastic collision, an object struck by a projectile will deform, and this deformation will absorb most or all of the force of the collision. Viewed from a conservation of energy perspective, the kinetic energy of the projectile is changed into heat and sound energy, as a result of the deformations and vibrations induced in the struck object. However, these deformations and vibrations cannot occur instantaneously. A high-velocity collision (an impact) does not provide sufficient time for these deformations and vibrations to occur. Thus, the struck material behaves as if it were more brittle than it would otherwise be, and the majority of the applied force goes into fracturing the material. Or, another way to look at it is that materials actually are more brittle on short time scales than on long time scales: this is related to time-temperature superposition.
Impact resistance decreases with an increase in the modulus of elasticity, which means that stiffer materials will have less impact resistance. Resilient materials will have better impact resistance.
Different materials can behave in quite different ways in impact when compared with static loading conditions. Ductile materials like steel tend to become more brittle at high loading rates, and spalling may occur on the reverse side to the impact if penetration doesn't occur. The way in which the kinetic energy is distributed through the section is also important in determining its response. Projectiles apply a Hertzian contact stress at the point of impact to a solid body, with compression stresses under the point, but with bending loads a short distance away. Since most materials are weaker in tension than compression, this is the zone where cracks tend to form and grow.
So I've been becoming pretty obsessed with base jumpers. However its a pretty dangerous sport and as it turns out (surprise) a lot of them die. I was just wondering how much force the human body can survive. Say a 90kg base jumper jumped off of a 900m mountain and their parachute failed to open...
I am very interest in knowing about how skin reduced force that can damage bone.
I guess it act like a protective layer by flexing and stretching such as a trampoline. Also skin redistribute the force and spread out evenly and the soft tissue play role here too. Please help if someone have any...
All,
I need your help, please...this is true
I was rear ended and I would like to know the impact force...
I was waiting for the car in front of me to turn left, so I had my foot on my brake, I was driving a 2004 Lexus RX330...call it 3500 lbs.
A large truck was texting and...
Hello All,
Some background information: I'm a co-op engineering student and recently my supervisor asked me to do a bit of research on a solution to a problem we had. Essentially, a cardan shaft connecting a motor and a gear box failed at a joint during operation and caused some extensive...
I am currently working on an experiment with piezoelectricity and was wondering how I would measure the force applied to the crystal. I have been tapping the crystal with a screw driver and was wondering how I would calculate the force of these taps as I cannot find the amount of displacement in...
Homework Statement
1200kg car moving at 9.72m/s runs into and sticks to a parked 1000kg car. The collision takes 0.15s and after the crash the cars wheels lock and they skid to a stop on u=0.40 road. What is the impact force on both cars?
Homework Equations
J=F*t=m*dv
The Attempt at a...
This is going to sound odd but I am hoping to use physics to defend an allegation made by my ex-wife. She alleges that I threw a knife into my kitchen sink and it bounced up and stuck into the ceiling (in reality I was overseas when the knife was broken by her brother - I'm just hoping to use as...
A moving car crashes with a tree. Will the impact force on the car by the tree equal to the impact force on the tree by the car?
Does Newton's third law apply here?
I am a M-tech student working on a project of Drop weight impact testing machine for measuring the crashworthiness of structure. As it will be a lab-scale model, the budget doesn't allow me to include load cells for measuring peak impact force by load-displacement graph.
I am planning to...
how would i go about calculating the peak force of an impact between two solids
i assume it has to do with the how readily the structure compresses but I am not sure what else might complicate it from there
also what if one of the objects fractures and what about granular impacts
Hi there,
I'm trying to work out how much force is produced if a climber was to fall onto a rope.
I do realize that it would depend on the rope and whether it stretched or not but for this case let's just say it does not have any give in it.
If I use the example of a climb who weighs...
Homework Statement
So this isn't a homework question, just something my brother-in-law asked me. He is in the Army, and wanted to know an approximate landing force he would experience when he lands. After attempting the problem, and looking things over, I realized it may be harder than once...
[b]1. What would be the effect on the impact force of a lower or higher release point of a metal ball in an inclined plane.
[b]2. I don't know what to do here.. or how to answer. My teacher told us to include formulas to prove our answers.
Homework Statement
This isn't for homework or anything like that, just something that happened to my mom around 2 years ago that I'm trying to calculate what forces she was subjected to.
She and my dad were walking the family dog (not that it's relevant, but I'm an adult and don't live at...
I been looking on google and getting help from several people who are trying to help me, but I just can't understand this. It is to advance for me as of now and I need a example to help show me. But I need this for homework so can someone help and provide formula explaining how this would. Be...
Can anyone recommend a device or way I can measure the impact protection qualities of different running shoes? I am a runner and would be interested in doing this myself.
I appreciate it!
scenario - A free falling body impacts water at terminal velocity. During what time period is the body considered to be in impact. I am trying to calculate the impact force alone. Is the impact force considered at the initial contact, during the body is fully transitioning from one medium to the...
I am doing a simple steel ball drop test on glass to see if the glass passes the standards.
We are dropping 1.18 inches (0.535kg) steel ball at the height of 51inches (1.295m).
Now, I can calculate final velocity at the impact, but cannot calculate the actual impact force.
One of the method...
Homework Statement
A vehicle falls 20 mm back onto a smooth steel track after going over a bump. It has polyurethane wheels. Young's modulus is known for both wheels and track materials. What is the force exerted by the vehicle onto the track as it lands?
Homework Equations
F = mdv/dt
KE =...
i need to work some estimations for this case for an assignment
30mph vehicle hits a bollard with 667kJ
bollard height = 1m
vehicle hits the bollard at approx height of 0.7m
material = mild steel
ultimate strength = 400mpa
in one case the bollard is 219mm ext diameter with 10mm wall...
Hi all, this is my first post on Physics forums so I apologise in advance if I have posted in the wrong section etc. This is something that I have been trying to figure out for nearly a week now! I have modeled a vehicle in Solidworks, specifically an external roll cage, and hope to conduct a...
I'm working on a small design project and need some help remember what equations to use here. Basically, we are creating a hammering device. A compression spring will be loaded, and a block on the end is accelerated into another block. I need to have it hit with a certain impact force so I am...
I often hear about collisions in terms of impact force. For instance, "the boxer delivered a punch with 100 lbs of force." I have a pair of steel toed shoes that are rated to withstand 70 lbs of force (311 N). But if the shoe experiences an impact instead of being loaded very gradually, wouldn't...
I used some formulas to determine the impact force of a bubble wrapped 1kg object dropped 1 meter and traveling .03m after impact. But I need some help with the next part. What if an identical bubble wrapped 1kg object is placed on top and both are dropped at the same time? Will the wrapping...
I'm doing a physics assignment on safety devices such as helmets and i need help with a question.
Why is the Impact force reduced for a helmet with a soft interior VS a hard interior?
I know it is because the soft padding on the inside of soft the helmet will reduce the time taken for your...
This one is actually for a lab assignment. In the experiment you shoot a jet of water upward vertically at a variety of targets with different geometries (a flat plate, various cups). The target is suspended from a rod, and on top of the rod is a cup where you can add weights, held up by a...
I am trying to determine the maximum (instantaneous) impact force experienced by an object when it is struck by a hydraulic ram. I know both the pressure in the cylinder side of the ram and the level of deceleration (-g) experienced by the end of the rod on the ram when it stikes the object...
Here is a question for the physics experts. Some people been debating about the impact force on a bike of a bike rider riding off a 6 foot drop to a flat landing. Mainly the debate is about if speed would lessen the impact force on the bike because of the impact angle.
So, if a bike rider...
I've been trying to figure this out for a few days now and I hope someone can help me out...If an object is lifted 1m above the rigid ground and then it is dropped.
What would be to force experience (in Newton) by the object if:
- You don't know the exact distant or time for the object to come...
Hi,
I am trying to calculate the impact force of a rubber weight falling on a rubber surface. I am aware that to calculate impact force, I need to know the amount of deflection after impact. Is there a way to calculate this, using material parameters, rather than experimentally?
Thanks in...
Homework Statement
[PLAIN]http://img87.imageshack.us/img87/9964/impactforceonbike.png
A roller is rolling with a constant speed before and after the drop. How do i figure out the impact force exerted on the wheel when it just touch the floor from a height h?
Assume, angular velocity...
first of all I have a case that is screwed in another case ,I like to know a basic way to calculate the impact force in the screws ,the are 16 screws, I try using the basic impact force formula and the conservation of energy in the free fall,but I am having problems since I don't have the D...
Trying to calculate the impact of an 8000 lb. truck moving at a rate of 55mph, hitting a 200 lb deer that is standing still in the middle of the road. Does assuming it is a localized hit make any difference? What i mean is, if the deer was hit from the back, and his 200lb wieght was focused in...
So a friend and I started a debate over dinner, and no-one around here really wants to side with either of us, since neither of us has any concrete facts on the issue. The issue is this: Which would have a greater chance of causing a fatal impact on someone, a wooden bat or an aluminum bat...
I recently received a speeding ticket for "allegedly" driving my scooter (Piaggio MP3 500) 72Mph on a stretch of road with a lower speed limit. I was traveling too fast and I deserve to pay a penalty; however, I am also hoping the judge will recognize that a speeding scooter is less potentially...
i'm trying to calculate the impact force of a slide hammer under water. i can calculate it in air using (mv^2/2d), from work energy principle info i got off the net. and i have formulas for calculating drag; (0.5CpAv^2), also off the net, which i believe i have to account for? but no idea how to...
There is a standard impact test that is used in the fenestration industry. An air cannon is used to fire a piece of lumber at the unit being tested. The mass of the 'missile' is 4.09 kg. The velocity of the missile is 15.26 m/s.
I am wondering if there is a way to approximate this test...
calculating impact force??
I need help calculating impact force. Here's all the information I have:
the object weighs 180 pounds
being dropped from a height of 11 feet
I'm not completely sure if the force can be determined from that. I'm having a hard time figuring it out for some reason.
Homework Statement
the question goes like this
a man of mass 70kg falls onto a rescue cushion from a height of 7 m he comes to rest 0.2s after he reaches the cushion the cushion is 2m high when inflated
a)find the impact force acting on him (take the weight of the man into...
I am trying to calculate the difference in force between a body standing still on the Earth's surface and that same body falling from a distance of 2.7 meters (approx 9 feet).
Specifically, I am trying to determine what percentage increase in force is attained by this fall.
Thank you.
Homework Statement
A cart is driving on straight tracks with a velocity of 2 m/s. In the opposite direction, with an angle of 60º according to the tracks, a child with a mass of 2 kg is running with a velocity of 2m/s, he jumps on the cart and stays there.
- Find the mass of the cart, if...
Hi,
I am performing a set of tests using a pendulum. The test involves a pendulum of length 0.55metres, the weight of the entire pendulum is 2kilos.
The test involves letting the pendulum go from a set height and calculating the force when it impacts an object held in a vice at the bottom...
Homework Statement
An aircraft is landing on a carrier ship in the middle of the Pacific. When the aircraft’s jump cable catches to stop the plane, the aircraft is traveling at 110 mph with the front of the plane 3 feet off the deck of the ship. If the assumption is made that the cable...
Hi,
Hopefully somewone will know the calculation to find out the impact force for one person sitting on a chair and falling backwards with a full deaceleraton to a hard floor, what would the impact force be to the base of he head when stricking the floor.
Chair is a chair with a bottom and...
First off, i don't know if this is the right section for this, just thought i would try though...
Here is my problem. I need a formula for impact force and duration when using spring pressure. I have the mass of the object in grams, the force of the spring, and the push length. Now i...
I'm trying to figure out what the stress level of a wakeboard is when it hits the water upon landing. I'd like to be able to compute the desired strength of a board if I were to make my own and how it would relate to the strength/thickness of fiberglass or carbonfiber around the core.
I have...
Hello Everyone, I'm hoping you can help with this.
I need to set up a test on a dynamic test rig which can simulate shock impacts upon a spring (actually it's a hard rubber based component).
The test has previously been done on a rig which dropped a mass of 78Kg onto the part until...
Homework Statement
I am creating a device to provide 250 to 300 g's of impact force to an electrical device in a plastic housing. I would like to lift a steel plate approximately 16" x 16" X thickness "T",, to a height of "Y" and release it. It would fall at the rate of gravity, impacting a...
I was wondering if anybody could help me. I need to calculate the impact force exerted on an rov if it collides with a oil well tree. The information I have are the mass of the rov = 500 kg, initial velocity othe rov is 1.5 m/s and the oil well tree is a fixed body. I am unsure how to calculate...