If they have the expected values in limiting cases.
The bal on the forearm exerts 59-N force, while the biceps on the forearm exerts 450-N force.
The force applied by the biceps is closer to the axis of rotation than the force applied by the lead ball.
The biceps would have to exert a larger force if the center of the forearm were farther from the elbow.
Biceps in the equation would mean that the bicep would need to exert force on the arm when lifting something.
The forces that were put on the system were put at the right angles.
Consider the next example.
A drawbridge across the mouth of an inlet on the coastal highway is lifted by a cable to allow sailboats to enter the inlet.
When the bridge attendant accidentally activated the bridge, you were driving across it.
You stopped the car at the end of the bridge.
The cable goes over the horizon tal bridge.
The mass of your car is 1000 and the mass of the bridge is 4,000.
Estimate the tension force that the cable exerts on the bridge as it slowly lifts it.
The situation should be low and the bridge should be used.
Since four objects exert axis of rotation where the drawbridge connects by forces on the bridge, the equilibrium will be dependent on the roadway at the left side of the bridge, as we have no information about that force.
Exploration as just started to rise, so it is 34,000 N and Discovery, 1e horizontal.
Pearson will assume that it is static.
The unit is correct.
It is unknown in magnitude and direction.
When the bridge is close to the axis of 53 angle above the horizontal, the cable on B should have a smaller Torque.
Our knowledge of equilibrium conditions allows us to understand how one can increase or decrease the turning ability of a force if they exert the force in a dif ferent location or in a different direction.
If you need to get a car out of a rut in the snow or mud, consider a situation.
Push the middle of the force that you exert on the rope.
Push from if you want to exert a large force on a stuck car.
The side on the tautly tied rope has to remain stationary for that small section of rope to remain stationary.
The rope exerts more tension than the force you exert on it.
If the backpack is not supported by a hip belt, each strap has to pull down on the trapezius muscle.
The force that the muscle exerts on its connection points is greater than the force that the strap exerts on it, just as the force that you exert pushing on the rope is greater than the force that you exert pushing on the rope.
A heavy backpack can cause injury.
On each side of the strap there is a strap muscle.
The trapezius muscle exerts force on its connecting points on the neck and shoulder like the rope to the tree and the car did.
The situation is shown in a sketch.
The system of interest is the section of muscle under the strap.
The force on the backpack is less than the force on the Earth.
A 70 kilo tightrope walker stands in the half of the rope exerts on a short section of rope beneath the middle of a tightrope that moves upward with each walker's feet.
A person has a backpack.
The person's trapezius muscle exerts a 240-N force on the bones that are attached to it.
You can sit on a living room couch without tipping for a long period of time.
For a short time interval, equilibrium can be achieved if you sit on a chair and tilt it back too far.
If you spread your feet apart in the di rection of motion, it is easier to balance and avoid falling in a moving bus or subway train.
You are watching the train from the ground.
The train is moving out from under them.
The left foot of each person is seen by the platform observer.
The earth's force on B causes it to recover from the tilt without falling.
The person falls if the feet are together.
The person recovers after the feet are apart.
If a vertical line passing through the object's center of mass is within the object's area of support, the object does not tip.
The object tips if the line is outside of the support area.
Testing our tentative rule about tipping.
The geometric center of mass is the center of mass.
If you release the slightly tilted can, it returns to the vertical position.
If you tilt the can more and more.
For a can with a diameter of 6 cm and a height of 12 cm, this angle matches the prediction.
The tipping rule states that if an object is in static equilibrium, the line must pass within the object's area of support.
The object tips over if it isn't in the area of support.
The Leaning force goes beyond the area of support as E on Tower passes through the base.
If the Tower of Pisa does not tip over.
Building con struction uses this idea a lot.
The Eiffel Tower has a wide bottom and a narrower top.
TheObservational Experiment Table 7.5 explains why you need to keep your feet apart when standing on a subway train.
There are several holes in the ruler.
The ruler swings back and forth with maximum displacement from the equilibrium position if you pul the bottom of the ruler to the side.
The ruler swings down if disturbed.
If the bottom of this ruler is released, it will return to equilibrium.
If the top of the ruler is stable.
There is no displacement that has displaced from equilibrium.
The axis of rotation does not exert any force on the ruler or the object.
The net force on the ruler by Earth and by the displaced is tipped over if the ruler is both positions a and b.
The center of mass of objects is usually lower when the Torques are produced.
If it is possible for the object to be tilted so that its center of mass is lowered, it will do so.
If we hang the ruler using the center hole, it stays in its original position.
The normal force that the nail exerts and the gravitati nail onal force that Earth exerts produce zero Torques.
The ruler has no effect on displacement.
Is it possible to balance the pointed tip of a pencil.
There is a sketch of the Net clockwise situation.
There is an E on P. The axis of rotation is the tip of the pen.
This instability is caused by F on P-K tation.
The pencil is shown below.
Try to understand new situations and ideas that are ready to be discussed.
The equilibrium is most stable when the center of mass of the system is in the lowest possible position or the smal est value.
Circus tricks are included in the rules of equilibrium and stability.
Vending machines are an application center of mass.
A bicycle on a high wire may not be as dangerous as it looks.
According to the U.S. Consumer Product Safety Commis- model the vending machine is just barely off sion, tipped vending machines caused 37 deaths between chine as a rigid body.
A vending machine that is 1.83 m high, 0.84 m deep, and 0.94 m wide is shown in the side view.
Four corners of its base are supported by a leg on the force diagram.
The back floor has an axis of rotation.
The person exerts force on the vending machine.
The vending machine that was erted by the floor on the back legs did not produce a will tip.
Both answers seem reasonable.
To keep the vending machine tilted above the horizontal, you need to just barely lift the vending machine's front off.
The chance of being injured by a tipped vending machine is small since a large force must be put on it to tilt it up, and it must be tilted at a fairly large angle before it reaches an unstable equilibrium.
In regions prone to earthquakes, falling bookcases is a more common danger.
The base of a bookcase is not very deep.
The bookshelves above the base are the same size as the base bookshelves.
The bookcase can tip over.
In earthquake-prone regions, people attach a bracket to the top of the bookcase and anchor it to the wall.
We will apply our understanding of static equilibrium to analyze three common situations: standing on your toes, lifting a heavy object, and climbing a ladder.
In a less stressed situation, we will analyze what happens to your ankle.
The magnitude of the force that the tibia exerts on the ground if you stand on your toes with your heel slightly is what it is.
We sketch the foot with the distance from the joint to the Achil es tendon attachment.
The system of interest is caused by the Torque condition of equilibrium.
A very light foot is a rigid body.
The force that Earth exerts on the foot is two and a half times the force that Earth exerts on the body.
We will ignore it because it's 10 N>kg for a 70 kilogram per ing.
The force diagram shows the force at 1750 N.
When moving, the forces are greater.
Every time you lift your foot to walk, run, or jump, the tendon ten sion and joint compression are more powerful than the force that Earth exerts on your entire body.
If the person's mass was 90 kilograms instead of 70 kilograms, the Achil es tendon on the foot of the person would increase in magnitude.
Let's apply equilibrium to this system.
A bad way to lift.
Improper lifting techniques can cause back problems.
The downward pul causes a large clockwise Torque on her upper body.
To prevent her from tipping over, her back muscles have to exert a lot of force.
The force of the back muscles can cause damage to the disks in the lower back.
The equilibrium equations can be used to estimate the lifting forces.
The axis of rotation is where the back muscle body is located.
A force dia is drawn in her lower back when she lifts a barbell.
133 kg219.8 N/kg2 is 323 lbs.
179 N 140 lbs2 is calculated using 118 kg219.8 N/kg2 and 176 N 140 lbs2 The force by which it is exerted makes a 12 angle relative to the horizontal backbone.
D doesn't produce a Torque.
The barbel exerts force on the upper distribution and the Earth exerts force on the upper distribution.
The axis of rotation is at the left end of the body, while the tension of the back muscles on the upper body represents one of the disks.
Our model of a person lifting a barbell is below.
The force that the disk exerts on the bone is the same as the force by the back of the disk.
The back muscles exert a force more than four times the grav out if the denominator of the terms in this equation is found.
Two linemen standing on a 1-inch-diameter disk are equivalent to M on B cos 12 tebral disk.
It's a better way to lift things.
Lift your legs with your knees.
The back muscle exerts a third of the force when it is not being lifted correctly.
The disks in the lower back are only half the size they are.
Consider the physics of using a ladder.
You want the ladder to remain static when you climb it.
The ex terior wall of the house is very smooth, meaning that it exerts a negligible friction force on the ladder.
The floor and ladder have the same coefficients of static friction.
We sketched the situation.
If the ladder is too large an angle from the vertical, it will slide down the wall.
The force diagram der and the painter should be used together.
Rather than determining the center of mass, we have kept the forces of Earth on the ladder and painter separate.
Ladder out of each seems reasonable and similar to what we do when someone uses a ladder in real life.
There is a warning not to have the angle exceed 15.
Earth exerts less force on the object being lifted than the muscles in the body do.
You can use your understanding of static equilibrium to get rid of this phenomenon.
A leaf flutters.
A chemistry book rests on top of a physics textbook.
You have an object that is irregular.
A hammock is between trees.
The ropes have an equal chance to break.
The objects are not in the axis of rotation.
Why do you tilt your body?
Give an example of an object that is moving quickly.
10 is the force that the body muscles exert on bones.
A ladder is leaning against a wall.
For each force, identify two interacting objects.
Is it possible that an object won't be in equilibrium when 22?
It takes a large example to pul ing directly on the nail.
Is it harder to do a sit-up with stretched hands?
The two conditions are not the same.
It's better to estimate the problem rather than make a specific answer.
You have to make a drawing or graph as part of your calculations.
This is your solution.
You have a computer.
The more difficult problems should be estimated.
The Torque that balances those produced by shown object O is caused by 3 on O.
A 100N force was found on the knot by 4 on O.
64 N is the B knot's location.
A ladder resting against a house wal makes a 30 angle with the wall.
Between the top of the ladder and the wall the coefficient of static friction is zero, while between the ladder feet and the ground it is 0.40.
Luis (rope 3) was ex- 13 The machine shop you work in needs a force that balances the first two so that the knot doesn't move the big engine to the left in order to slide.
The rope- pulling exercise described in the previous two problems was joined by Kate.
They tied four ropes to the ring.
The ring should be in equilibrium with 4 on R. You exert a 630@N force on rope 2 in the previ and use the first condition of equilibrium to write a two-equa ous problem.
If you replace the light in safe, the ropes will exert on the knot.
The rope length is 20 m and the problem is with a heavier object and ropes.
The numbers 2 and 3 are shown in Figure P9.
If the tension of Chapter 7 exceeds 6700 N, the rope will break.
A man is sitting on one end and the other.
A woman sits on the other end of an apparatus to lift hospital patients.
You have a flat tire.
If subjected to a Torque greater than 3300 N#m, ject A will break.
The bers in Figure P7.24 seesaw are 1.2 m from the ground.
You are standing at the end of a diving board.
You can make a list of physical quantities and show how you will change them with different dimensions.
You put one penny in the bottom left cup, three pennies in the bottom right cup, eleven pennies in the middle right cup, and five pennies in the top left cup.
Kate is sitting on a swing.
Kate sits on the right side of the swing because it is wet on the left side.
Kate's mass is 55 kilo and the swing seat's mass is 10 kilo.
The two cables exert force on the swing.
Ray decided to paint the outside of his uncle's house.
He uses a board supported by cables to paint the second floor.
The board has a large mass.
Ray is 1.0 m from the left cable.
You put a board across a chair to seat three.
A group of physics students are at a party at your house.
2.5 m from one end is where Dan sits.
Komila needs to balance the seesaw by sitting at the other end of the board.
The table exerts force on the bag of vegetables at one end and the bag of fruit hand at the other end.
2 at the right when you lift a barbel.
A person has a broken leg.
A person is standing at one end of a boat.
The block 80 cm with respect to the bottom of the lake should be the size of the rope pulling on the leg if the boat moves so fast that it exerts a 120@N force on it.
Two people are holding hands and standing on erblades.
A person with a height of 1.88 m is lying on a light board with scales under their feet and under their head.
When he bends over 43, estimate the location of the per son's center mass.
He is touching the floor with his hands while you are working out.
A seesaw has a mass of 30 kg, a length of 3.0 m, and a fulcrum cord attached to a hook on the wall.
Determine the mag on one end and a person sits on the other.
The thigh bone exerts on the calf bone at the knee joint.
You have a 10 kilo table with each leg of mass 1.0 kilo.
A man is holding a child with both hands and his elbow bent 90 degrees.
Determine the force that each of his muscles must exert on the forearm in order to hold the child in this position.
You use the ar of the arm to hang the flowerpot.
The force that his triceps muscle must exert on his forearm is not known, but it looks light.
It is much easier to push a rock than it is to pull in an experiment.
You can draw a picture to explain your decision.
You are trying to tilt a very tal refrigerator so that your friend can put a blanket under it to slide it out of the kitchen.
You need to exert force on the front of the 45.
At the start of its tipping, you decide to hang another plant from the refrigerator.
The horizontal y horizontal beam is attached to the wal by a hinge above the floor.
A cable goes above the beam.
A machine with two blocks each of mass is connected to a wall by a hinge.
The string goes from the beam to the wal.
You let it go while pul ing down on one block.
You are on a moving train.
The beam is at a 37 thing.
The force that the cable exerts on the beam is determined by your back at work.
Determine the forces that support posts 1 and 2 exert on the board when a person is standing on the end of the board.
The box is on the floor with the edge pressing against a ridge.
If two different magnitude forces are put on the same object, their rotational effects can be canceled if they are the same magnitude but opposite sign.
The cable is horizontal.
The cable is horizontal.
Two experiments are needed to determine the mass of a ruler.
The 60 are your available materials.
She has a barbell in her hand.
The center of mass of her arm and the table is m and the board is m.
A person is on a tightrope.
Two balls hang from 0.50@m-long strings at each end of the bar.
Indicate the assumptions made for each part of the problem.
A professor sits on a chair.
The barbel has a rope attached to it.
Determine both the force that the deltoid exerts on end of the beam and the force that the lifter's shoulder joint wraps around the professor.
There is a football running in the middle of the beam.
The axis of rotation has the center of mass in front of it.
The head/helmet is balanced by the Torque caused by the downward forces exerted by a complex muscle system in the neck.
The trapezius and levator scapulae muscles are included in the muscle system.
A person is on a ladder.
The hori ladder is tilted 60 above the horizontal and you hold a 10-lb bal in your hand.
The upper arm has a 90 angle with the coefficients of zontal.
The ladder has a mass of 10 kg and a length of 6.0 m.
There is a ladder against a wall.
It's easier to hold a heavy object with a bent arm than it is with a 70.