# Posts by hannah

Total # Posts: 3,341

1)A 1180-kg van, stopped at a traffic light, is hit directly in the rear by a 753-kg car traveling with a velocity of +1.81 m/s. Assume that the transmission of the van is in neutral, the brakes are not being applied, and the collision is elastic. What is the final velocity ...

A car (mass = 1140 kg) is traveling at 27.3 m/s when it collides head-on with a sport utility vehicle (mass = 2380 kg) traveling in the opposite direction. In the collision, the two vehicles come to a halt. At what speed was the sport utility vehicle traveling? I did 1140(27.3...

1)A 1180-kg van, stopped at a traffic light, is hit directly in the rear by a 753-kg car traveling with a velocity of +1.81 m/s. Assume that the transmission of the van is in neutral, the brakes are not being applied, and the collision is elastic. What is the final velocity of...

A high-jumper clears the bar and has a downward velocity of -6.00 m/s just before landing on an air mattress. The mass of the high-jumper is 53.7 kg. What is the magnitude and direction of the impulse that the air mattress exerts on her? Assume that upward is the positive ...

Four very thin rods, each 8.3 m long, are joined to form a square. The center of mass of the square is located at the coordinate origin. The rod on the right is then removed. What are the x- and y-coordinates of the center of mass of the remaining three-rod system? I have no ...

1) A man (mass = 80.9 kg) jumps straight down from a bridge into a boat (mass = 482 kg) in which a criminal is fleeing. The velocity of the boat is initially +14.5 m/s. What is the velocity of the boat after the man lands in it? would I subtract the two masses and then ...

1) David has a mass of 86.4-kg and is skating with in-line skates. He sees his 24.8-kg younger brother up ahead standing on the sidewalk, with his back turned. Coming up from behind, he grabs his brother and rolls off at a speed of 2.99 m/s. Ignoring friction, find david'...

1) A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force) acts on her. The student has a mass of 71 kg, and the height of the water slide is 12.0 m. If the kinetic frictional force does -7.4 × 10^3 ...

I got 10.68 as my answer but my homework said this was incorrect.Why?

A skier slides horizontally along the snow for a distance of 11.9 m before coming to rest. The coefficient of kinetic friction between the skier and the snow is 0.0458. Initially, how fast was the skier going? I do not know how to start this. Thank you. Physics(Please help...

Disregard question. I got the answer. -63072.23

I got 897.45 = 99772.23 + KEf I subtracted 99772.23 from both sides and got -98874.78 for KEf. Did I do this correctly?

1) A roller coaster (398 kg) moves from A (3.82 m above the ground) to B (29.4 m above the ground). Two non-conservative forces are present: friction does -1.82 x 104 J of work on the car, and a chain mechanism does +5.49 x 10^4 J of work to help the car up a long climb. What ...

Disregard question.

so I did (1/2)(83.9)(10.1-6.3) and got 159.41 J.Is this correct?

A water-skier is being pulled by a tow rope attached to a boat. As the driver pushes the throttle forward, the skier accelerates. A 83.9-kg water-skier has an initial speed of 6.3 m/s. Later, the speed increases to 10.1 m/s. Determine the work done by the net external force ...

For the values of mg, m would be 398kg and g is 9.8 correct?

1) A roller coaster (398 kg) moves from A (3.82 m above the ground) to B (29.4 m above the ground). Two non-conservative forces are present: friction does -1.82 x 104 J of work on the car, and a chain mechanism does +5.49 x 10^4 J of work to help the car up a long climb. What ...

So for v would I do sqrt(2*11.9*9.8*0.0458) ?

A skier slides horizontally along the snow for a distance of 11.9 m before coming to rest. The coefficient of kinetic friction between the skier and the snow is 0.0458. Initially, how fast was the skier going? I do not know how to start this. Thank you.

So for m I would plug in 71kg correct?

so for m

A student, starting from rest, slides down a water slide. On the way down, a kinetic frictional force (a nonconservative force) acts on her. The student has a mass of 71 kg, and the height of the water slide is 12.0 m. If the kinetic frictional force does -7.4 × 103 J of...

A 12-kg crate is pushed up an incline from point A to point B. What is the change in the gravitational potential energy of the crate? Point A is 2.0m and point b is 7.0m I am not sure how to start this.

Were these right???????

I did the math wrong, I got 103 now.

Is that correct?

so on the left side of the equation the mass is gone and on the right side the mass and gravity is gone. So the anwser would be 784h = 1800 h=2.2

a rollar coaster is 80m high and has a 50kg car at rest. Ignore air resistance and friction. If the speed of the car is 60m/s what is the height? 0+50(9.8)(80) = 1/2(50)(vf^2) + (60)^2 + 50(9.8)(h). Is this equation correct?? If so I do not know how to solve for h since on the...

so m=1320kg and v=3.32^2 but what is r and mg?

1) A 1320 kg demolition ball swings at the end of a 34.3 m cable on the arc of a vertical circle. At the lowest point of the swing, the ball is moving at a speed of 3.32 m/s. Determine the tension in the cable. F=ma (34.3)(3.32) = 113.87 Ia this correct?

A jet flying at 106 m/s banks to make a horizontal circular turn. The radius of the turn is 3810 m, and the mass of the jet is 2.40 × 105 kg. Calculate the magnitude of the necessary lifting force. Would I use the equation Fc=mv^2 / r ??

1) A box is sliding up an incline that makes an angle of 14.0 ° with respect to the horizontal. The coefficient of kinetic friction between the box and the surface of the incline is 0.176. The initial speed of the box at the bottom of the incline is 3.72 m/s. How far does ...

A golfer hits a shot to a green that is elevated 3.0 m above the point where the ball is struck. The ball leaves the club at a speed of 17.4 m/s at an angle of 35.0¢ª above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...

A golfer, standing on a fairway, hits a shot to a green that is elevated 5.33 m above where she is standing. If the ball leaves her club with a velocity of 48.0 m/s at an angle of 35.7 ° above the ground, find the time that the ball is in the air before it hits the green...

I meant (17 sin 35)^2

so for vy I would do (17.4 sin 35) - 2(9.8)(3) ??

A golfer hits a shot to a green that is elevated 3.0 m above the point where the ball is struck. The ball leaves the club at a speed of 17.4 m/s at an angle of 35.0¢ª above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...

so is 79.2 kg the value for mass(m) or mg?

A 79.2-kg person stands on a scale in an elevator. What is the apparent weight when the elevator is (a) accelerating upward with an acceleration of 1.92 m/s2, (b) moving upward at a constant speed, and (c) accelerating downward with an acceleration of 1.89 m/s2 I was going to ...

A golfer hits a shot to a green that is elevated 3.0 m above the point where the ball is struck. The ball leaves the club at a speed of 17.4 m/s at an angle of 35.0¢ª above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...

Physics(thank you for the help)
A hot-air balloon is rising upward with a constant speed of 2.45 m/s. When the balloon is 3.22 m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before the compass hits the ground? I know that average speed ...

1) A cave explorer drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 1.33 s after the stone is dropped. How deep is the hole? I did 343 / 1.33. Is this correct? Physics(Please help) - drwls, ...

Physics(thank you for the help)
I do not know how to solve for a ratio.

Physics(thank you for the help)
1) A baby elephant is stuck in a mud hole. To help pull it out, game keepers use a rope to apply a force FA. By itself, however, force FA is insufficient. Therefore, two additional forces FB and FC are applied. Each of these additional forces has the same magnitude F. The ...

A pilot flies her route in two straight-line segments. The displacement vector A for the first segment has a magnitude of 254 km and a direction 30.0o north of east. The displacement vector for the second segment has a magnitude of 178 km and a direction due west. The ...

Physics
1) A jetliner, traveling northward, is landing with a speed of 69.3 m/s. Once the jet touches down, it has 787 m of runway in which to reduce its speed to 13.6 m/s. Compute the average acceleration (magnitude and direction) of the plane during landing (take the direction of ...

When I put 21.792 m/s as my answer my online homework said it was incorrect. Why??

Determine the final speed assuming that the time elapsed since t=0 is 2.4s. Initial velocity is +12m/s acceleration is +3.4m/s^2 I tryed doing 12/2.4 and then 12/3.4 but both of these were incorrect? I am not sure what to do. Thank you.

For some reason when i put in 5.4 as the answer it said I was incorrect. I do not know why.

1) The velocity of a diver just before hitting the water is -11.8 m/s, where the minus sign indicates that her motion is directly downward. What is her displacement during the last 1.06 s of the dive? I know that the formula for displacement is deltaX= x - x0. Would I do -11.8...

So I would set my problem up as (13.3 - X/343)^2 = x/1.76 The only thig I am not sure of is how to solve for the x.

1) A cave explorer drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 1.33 s after the stone is dropped. How deep is the hole? I did 343 / 1.33. Is this correct?

1) A penny is dropped from rest from the top of a very tall building. Assuming the height of the building is 407 m and ignoring air resistance, find the speed with which the penny strikes the ground. I am not sure how to start this. Thank you!

How do you know when to use tan instead of cos or sin?

1) two hot-air balloons are 48.2 m and 61.0 m above the ground. A person in the left balloon observes that the right balloon is 13.3° above the horizontal. What is the horizontal distance x between the two balloons? The left balloon is 48.2m and the right balloon is 61.0m...

Physics
1)A force vector points at an angle of 12.4 ° above the +x axis. It has a y component of +337 newtons (N). Find the magnitude and the x component of the force vector. For the x component I did 337cos(12.4)=329.13 N For magnitude I am not sure what to do.

1) A force vector has a magnitude of 579 newtons and points at an angle 43o of below the positive x axis. Find the x scalar component and the y scalar component of the vector? For the x component I did 579cos(43) = 423.45 N. Is this correct? For the y component I did 579sin(43...

A football is kicked with a speed of 18 m/s at an angle of 65° to the horizontal. How long is the football in the air? Neglect air resistance Would I use the equation y=y0 + voy t -1/2gt^2 ?

1) Which components remain constant throughout the motion? vx = x component of the velocity vy = y component of the velocity ax = x component of the acceleration ay = y component of the acceleration I know that ax and ay remain constant but I am not sure about vx and vy. Thank...

There is a diagram of a ball being thrown in a horizontal diection at 30m/s and there is an angle of 48degrees and a side with 4m. How long is the ball in the air? I am confused because I am not sure of the equation. I know that is is something like y = yo + ? - 1/2gt^2 Thank...

statistics (college
An insurance company checks police records (in a city) on 500 accidents selected at random and notes that teenagers were at the wheel in 120 of them. It is desired to test if this information indicate that more than 20% of auto accidents involve teenage drivers in the city. ...

Calculus
Integrate e^((x^3)/2) How do I start? I know that the integral of e^x is just e^x plus C, but what do I do with the ((x^3)/2)? Thanks!

pre calculs
Is that supposed to be f(x)=3x^2-7x-2?

Physics
1) Which components remain constant throughout the motion? vx = x component of the velocity vy = y component of the velocity ax = x component of the acceleration ay = y component of the acceleration I know that ax and ay remain constant but I am not sure about vx and vy.

Mathematics I
Evaluate definite integral from -2 to 0. Integral((x^2)(e^((x^3)/2)dx) Do those parentheses make sense? The power of e is x^3 divided by two. Can someone give me the first step, and I'll see if I can get it from there. I don't want to make you just do the problem for ...

physical sciences
Carbon has an atomic number of 6, which means it contains 6 electrons. To find the number of neutrons, just subtract the atomic number from the mass number. So 14-6 = 8. There are 8 neutrons in an atom of carbon with a mass number of 14.

Chemistry
Why do chloride ions increase corrosion?

Physics
Thank you!!

Physics
Vector A has magnitude of 9.77 units and points due east. Vector B points due north. 1) What is magnitude of B, if the vector A+B points 34.7 north of east? 2) Find magnitude of A+B I am not sure what formulas to use for this. If someone could show me how to start this I will ...

Which equations are dimensionally correct? F=ma E=max X=(1/2)at^3 V=sqrt(2*fx/m) E=(1/2)mv I think that F=ma , E=(1/2)at^3, V=sqrt(2*fx/m) are correct. Would you agree?

thank you!

A force, F1 of magnitude 2.0N and directed due east is exerted on an object is F2=2.0N due north. What is the magnitude and direction of a third force, F3, which must be exerted on the object so that the resultant force is zero? I am not sure how to start this problem!! Thank ...

Math
The circumference of the front tire is 6ft. How many complete turns does the front wheel make in 30 ft driveway?

math
Compute: The number of combinations of 8 elements taken 3 at a time. The number of permutations of 8 elements taken 3 at at time.

I know the highest point would be 29.4 but I do not know how to get this.

Ok but where did the 9 come from?

1) How long does it take the ball to reach its highest point? I am not sure what I would divide 24 by to find this. 2) How high above the starting point is the highest point? I am not sure how to find this.

A 5-kg ball is thrown straight up in the air with an initial speed of 24m/s. After its release and before it hits the ground when is the ball in free fall? My answer is at all times. Is this correct? Thank you.

Thank you!

Two vectors have magnitudes 4m and 3m. Which choice is not a possible magnitude for their resultant? 3m, 1m, 7m, 12m I chose 12m. Is this correct?

why is sin negative?

Vector A has a magnitude 2.4m and direction 130 degrees relative to the positive x-axis. Vector B has magnitude 3.0m and direction 250 degrees relative to the positive x-axis. 1) The resultant R=A+B has magnitude(in m) ? I know the R =2.75m but I am not sure how to get this. I...

math
ok thank you!

math
4 and 505/1000. but how does that help with this?

math
calculate 10^1.27 how do i do this?

Math
One bag contains 5 red marbles, 4 blue marbles, and 3 yellow marbles, and a second bag contains 4 red marbles, 6 blue marbles, and 5 yellow marbles. If Lydia randomly draws one marble from each bag, what is the probability that they are both not yellow?

Chemistry
A patient with untreated diabetes may have a blood concentration of acetone of 20mg/100mL. Determine the molar mass of acetone and use this number to convert this concentration to mol/L. Okay, so I was able to determine the molar mass of acetone (= 58.09g/mol) however, i'm...

physics
is increasing the current a valid method to increase the induced voltage when a magnet moves into a solenoid?

0.0885 - x = 4.2e-7 Then I added 0.0885 to the right side and got 8.85e-2. Would this be the concentration or do I need to do another step?

Calculate the concentration of HCO3- in an aqueous solution of 0.0885 M carbonic acid, H2CO3 (aq). I was going to set this up as 0.0885 -x = ? Am I suppose to use the Ka value for carbonic acid?

I multiplied 0.119 by 1.58e-10 and then took the square root, is that correct?

I did 1.0e-14 / 6.3e-5 = 1.58e-10 Then would I do (1.58e-10)(0.119)?

A 23.9 mL sample of 0.283 M trimethylamine, (CH3)3N, is titrated with 0.207 M hydrochloric acid. At the equivalence point, the pH is? I started off by doing 0.283 X 2.39e-2 = 6.76e-3 Then I did 6.76e-3 / 0.207 = 3.36e-2 2.39e-2 + 3.36e-2 = 5.65e-2 6.76e-3/5.65e-2 = 0.119 I do ...

surface area and volume
number 2 is wrong its b. 707 yd^2.

What is the molar solubility of barium phosphate in a 0.282M barium acetate solution? If I set up and ice table I would have 0.282M - X = ? Would I use the molar mass of barium acetate to complete the equation to find X? Ba3(PO4)2 ==> 3Ba^2+ + 2PO4^3- Ba(C2H3O2)2 ==> Ba^...