Average force Definition and 178 Threads

Homework Statement What is the magnitude of the average force required to stop an 1500kg car in 8.0s if the car is traveling at 75km/h ? Homework Equations The Attempt at a Solution

Hi all. I am marking GCSE paper that I did myself. There is 1 problem that I do not seems to understand. Please help me. Thank you very much. Homework Statement Daniel pulls a 3kg box up a slope from rest as shown (Attached) Given that the average friction of a slope is 2N and the speed at...

Homework Statement A block of mass 2 kg starts from rest and begins to move at time t=0 along a straight line on a smooth horizontal surface. The displacement of the block, s, depends on time, t, given by s=3+2t+t^3 . t is expressed in second and s in meter. Calculate the average force acting...

Homework Statement A ball of mass m bounces between two parallel walls, such that its velocity v is perpendicular to the walls.The collisions with the walls are totally elastic. What is the average force exerted by the ball on the walls, if the distance between the walls is d? Homework...

I solved the question , but i need to check it with you guys ... I believe there is something wrong with part b . Homework Statement The 15000kg train A is running at 1.5 m/s on the horizontal tack (to the right) when it encounters a 12000kg train B running at 0.75m/s toward it (to the...

Homework Statement Steel ball with a mass 17 grams, is launched at a speed of 6 m/s, into someones eye. The ball comes to a rest over a distance of 1mm. A) What is the average acceleration experienced by the ball to stop it? B) What is the deaccelerating force that must be exerted on...

Homework Statement Superman (m = 90 kg) jumps over a 78 m tall building by first accelerating from rest to his maximum velocity in 0.004 s. Subsequent to this time, Superman follows normal projectile motion. What is the average force acting on Superman that gives his upward acceleration...

Homework Statement We have to make a roller coaster for our school project. This coaster starts with a spring. In this coaster, there is a collision. Essentially, I need to find the energy lost at the collision, and the average force of friction. Homework Equations Em1=Em2 W=Fd F=ma A=DELTA v/...

Hey guys! I find it confusing to prove "mv^2/L", the average force acted by the air molecules on a wall in a box. My textbook tells me an assumption "the time during each molecules colliding with the wall of the container is negligible compared with the time elapsed between successive collision"...

Homework Statement A car of mass 10 kg hits another car at 10 m/s and they both come to rest at the same time. In the process, the car that was hit moved back 10 meters. What is the average force exerted on it? Homework Equations Average force = change in momentum divided by time...

Homework Statement Suppose that a seat-belted mother riding in an automobile holds a 10 kg baby in her arms. the automobile crashes and decelerates from 50km/h to 0 in .1 s. what average force would the mother have to exert on the baby to hold it?? do you think she can do this? Homework...

Homework Statement What is the average force applied by a 75 g bullet that leaves a gun at 1350 m/s and hits a target 75m from the barrel of the gun? Homework Equations F = ma The Attempt at a Solution First I had the equation F = ma, and began filling in all the variables I could...

Homework Statement A superball is to bounce elastically back and forth between two rigid walls at a distance d from each other. neglecting gravity and assuming the velocity of superball to be horizontal .Find the average force being exerted by the superball on each wall is ?Homework Equations...

A 1,662 kg car goes from 14 m/s to 29 m/s in 19 secs. What is the average force acting upon it? Write your answer to two decimal places. Attempt: Mass = m = 1,662 kg Initial Velocity = Vi = 14 m/s Final Velocity = Vf = 29 m/s Time = t = 19 secs Acceleration = a = Δvelocity/time =...

I just want to make sure I'm understanding negative work correctly. An example problem where there is a bullet with an initial velocity of x m/s and a final velocity of 0 m/s. It is stopped by a wood block and the question asks to determine the amount of work done on the bullet by the block. If...

I was given this question in a practice assignment; A 31.0 kg child on a swing reaches a maximum height of 1.92 m above her rest position. Assuming no loss of energy: 1.At what point during the swing will she attain her maximum speed? 2.What will be her maximum speed through the...

Homework Statement A typical flying insect applies an average force equal to twice its weight during each downward stroke while hovering. Take the mass of the insect to be 10 g, and assume the wings move an average downward distance of 1.0 cm during each stroke Assuming 100 downward strokes...

Homework Statement A 89.6 kg man steps off a platform 4.52 m above the ground. He keeps his legs straight as he falls, but at the moment his feet touch the ground his knees begin to bend, and, treated as a particle, he moves an additional 0.88 m before coming to rest. Treating our rigid...

Need to find the net force and the average force... 1. Homework Statement A bullet of mass 12 g strikes a stationary fixed block of wood at a speed of 400m/s, penetrating to a depth of 3.0cm. Calculate the average net force acting on the bullet while it is in the wood. Calculate the average...

A set of crash tests consists of running a test car moving at a speed of 11 m/s (24.2 m/h) into a solid wall. Strapped securely in an advanced seat belt system, a 57 kg (125.4 lbs) dummy is found to move a distance of 0.81 m from the moment the car touches the wall to the time the car is...

Homework Statement Two girls are arguing about which is able to hit a hockey ball harder. Describe an experiment which they could carry out to measure the average force between the stick and ball during time of contact. Homework Equations Force * Time=Change in Momemtum (Mv-Mu) The...

I have to deliver this problem resolved in 4 hours, I didn't think it was going to be so hard... Homework Statement A man of mass M is on the top of a balance with a very high damping coefficient. In a given instant he throws a ball of mass m vertically, catching it again later. a)...

Homework Statement A 0.25 kg ball, initially at rest, is hit with a bat in the x-direction while held 1.00 meter above the ground. If the ball hits the ground 20 meters away and was in contact with the bat for 0.10 sec, What average force was exerted on the ball during the contact time...

Homework Statement A 8.0×10−2 kg arrow hits the target at 25 m/s and penetrates 3.8 cm before stopping. Homework Equations What average force did the target exert on the arrow? What average force did the arrow exert on the target? The Attempt at a Solution I found the...

Homework Statement A projectile of mass 0.656 kg is shot straight up with an initial speed of 25.4 m/s. (a) How high would it go if there were no air resistance? (b) If the projectile rises to a maximum height of only 7.64 m, determine the magnitude of the average force due to air...

Not sure why my threads are closed ? As I think this needs an answer. To be honest, I do not think most here might have understood the question; let me explain the answer for you. Imagine a giant Butterfly, one Butterfly flaps their wings once up for a height of 3m, taking 3 seconds, and then...

Homework Statement An engine supplies an upward force of 9.00N to an initially stationary toy rocket, of mass 54.0g, for a distance of 25.0m. The rocket rises to a height of 339 meters before falling back to the ground. What was the magnitude of the average force of air resistance on the...

Dear all, it seems like I cannot reply to my thread, could we please open it again, as I need to be poilte and answer some of the questions the members asked me. https://www.physicsforums.com/showthread.php?p=3200023#post3200023 Yes, you have explained and many others have that no work...

Homework Statement A tennis player strikes a tennis ball of mass 56.7g when it is at the top of the toss, accelerating it to 68.0m/s in a distance of 0.0250 m. What is the average force the player exerts on the ball? Ignore any other forces acting on the ball. Homework Equations...

Energy/calories and average force. If you look in all Nutrition books and sites, you use/burn far far far more energy/calories when doing the same activity twice as fast. However someone says as the average force is the same in the below example, that you use the same energy/calories, I say...

Homework Statement A .140 kg baseball traveling 35 m/s strikes the catchers mitt, which, in bringing the ball to rest, recoils backward 11 cm. what was the average force applied by the ball on the glove? Homework Equations The Attempt at a Solution ughh i have really no idea. i...

how can this be average force ? The short of the question, is which puts the most tension on the muscles ? Some people say, that if you lift a weight, as in weightlifting/bodybuilding. Slow repetition, up 1m and down 1m, one time at 3 seconds up and 3 seconds down, and let’s call it a 100...

Question: A 0.165kg baseball pitched horizontally at 34.5 m/s strikes a bat and is popped straight up to a height of 40.0m. a) If the contact time between bat and ball is 1.0ms, calculate the magnitude of the average force between the ball and bat during contact. I got this part right. I...

Homework Statement a proton (m= 1.67 x 20E027kg) that has a speed of 5.0 x 10E6m/s passes thru a metal film of thickness 0.010mm and emerges with a speed of 2.0 x 10E6m/s. how large an average force opposed its motion thru the film? Homework Equations KE=.5mvE2 P=mv (momentum)...

Homework Statement A 75Kg man jumps from a window 1.0m above the side walk. if the man jumps with his knees and ankles locked, the only cushion for his fall is approximately 0.50cm in the pads of his feet. Calculate the average force exerted on him by the ground in this situation...

heya :) Homework Statement (Q)A ball of mass m is dropped onto a floor from a certain height. The collision is perfectly elastic and the ball rebounds to the same height and again falls. Find the average force exerted by the ball on the floor during a long time interval. Homework Equations...

average force if jumping off a building? Homework Statement A 75.0-kg stuntman jumps from a balcony and falls 25.0 m before colliding with a pile of mattresses. If the mattresses are compressed 1.00 m before he is brought to rest, what is the average force exerted by the mattresses on...

Homework Statement A 0.15 kg baseball is pitched with a speed of 23 m/s. When the ball hits the catcher's glove the glove moves back by 0.044 m as it stops the ball. Assuming a constant acceleration of the ball, what was the average force applied by the catcher's glove? Homework Equations p...

Homework Statement Air in a 140 km/h wind strikes head-on the face of a building 60 m wide by 50 m high and is brought to rest. If air has a mass of 1.3 kg per cubic meter, determine the average force of the wind on the building. Homework Equations The book seems to suggest the impulse...

Homework Statement A cyclist intends to cycle up a 8.2^\circ hill whose vertical height is 180 m. The mass of the bike and the cyclist is 95kg. If each complete revolution of the pedals moves the bike 4.7 m along its path, calculate the average force that must be exerted on the pedals...

Homework Statement The 2kg head of an axe is moving at 60m/sec when it strikes a log. If the blade of an axe penetrates a 20mm into the log, find the average force it exerts. m= 2kg V= 60m/sec d= 20mm or 0.02m Homework Equations F= pFINAL - pINITIAL / time t= d/v The Attempt...

Calculate the average force F acting on car Homework Statement A car does the work Wcar=5.9x105 J in traveling a distance x=6.3 km (6300 m) at constant speed. Calculate the average force F (from all sources) acting on the car in this process. Homework Equations Work = Force x...

Homework Statement A tennis ball has a mass of 0.057 kg. A professional tennis player hits the ball hard enough to give it a speed of 44 m/s (about 99 miles per hour.) The ball moves toward the left, hits a wall and bounces straight back to the right with almost the same speed (44 m/s). As...

Hi all. I have been thinking about this problem for quite a while now. Still kinda clueless. We know that when we apply electromagnetic radiation on an atom/molecule, then depending on the frequency of the radiation the atom/molecule makes electronic transition. We know how to get the average...

Homework Statement A 3.72 kg steel ball strikes a massive wall at 15.1 m/s at an angle of 58.6 with the plane of the wall. It bounces off with the same speed and angle. If the ball is in contact with the wall for .198s what is the average force exerted on the ball by the wall? Answer in...

Okay we all know that the average force equation is ΔP = FΔT F = ΔP / ΔT Say I throw a ball at the wall and it has and the collision is elastic. Therefore, the initial momentum equals the final momentum and therefore. ΔP = 0 I still know that there is a force exerted on the wall...

Part 1.) 1.35g bullet leaves the barrel of the gun going 270m/s. What is its kinetic Energy? -I converted 1.35 g to kg = 0.00135g -I arrived with an answer of 49.2075 J Part 2.) If the length of the barrel of the gun described above is 35cm, find the average force...

Homework Statement ...Suppose an oxygen molecule (m=5.32E-26 kg) traveling at this speed (\nu_{rms}=484 m/s) bounces back and forth between opposite sides of a cubical vessel 0.10 m on a side. What is the average force the molecule exerts on one of the walls of the container? (Assume that the...

Homework Statement In a performance test two cars take the same time to accelerate from rest up to the same speed. Car A has a mass of 1400 kg, and car B has a a mass of 1900 kg. During the rest, which car: a)Has the greatest change in momentum? b)Experiences the greatest impulse? c)Is...

Hi all, Question 1, If my 1RM {RM is the most I can lift, repetition maximum} is 200 pounds, and if I accelerate 160 pounds {80%} with a force of 200 pounds 80% of a mile or metre, or any distance, {it’s a weightlifting rep if you would like to know} and use the other 20% to decelerate and...