Kinematics Definition and 1000 Threads

Homework Statement The velocity of particle is 0 at t=0. Then , (a) The acceleration at t=0 must be zero. (b) The acceleration at t=0 may be zero. (c) If the acceleration is 0 from t=0 to t=10 s , the speed is also zero in this interval. (d) If the speed is 0 from t=0 to t=10 s...

1-D Kinematics Problem/Free Fall. "A helicopter carrying Dr. Evil..." NOTE: I'm new here and I wanted to make sure I am not breaking the rules: I show most of my work step by step for this problem since there are so many things going on in it. My question is whether or not my though process is...

A runner hopes to complete the 10,000m run in less than 30.0 minutes. After exactly 27.0 minutes, there are still 1100m to go. The runner must then accelerate at 0.20m/s^2 for how many seconds in order to achieve the desired time. I have calculated the runner moving at 5.5m/s^2 for the...

why does this kinematics problem seem impossible.HELP! Homework Statement If the man's mass is 70 kg, if L is 0.4 m h is 0.6 m, what is the downwards force (assumed constant) exerted by his feet during the phase A to B? State any physical law or principle you use in obtaining your answer...

Hi there, Sorry for so many questions, but I feel frankly stupid for getting these wrong, and yet I have no clue why they're so off. Any ideas of why the answers are what they are? Thanks so much. 15. A truck starts from rest and accelerates at 1.5 m/s2for 20 s. It then travels at constant...

Homework Statement At a carnival, you can try to ring a bell by striking a target with a 9.00 kg hammer. In response, a 0.400 kg metal piece is sent upward toward the bell, which is 5.00 m above. Suppose that 25.0% of the hammer's kinetic energy is used to do the work of sending the metal...

Homework Statement An extreme skier, starting from rest, coasts down a mountain that makes an angle of 25.0° with the horizontal. The coefficient of kinetic friction between her skis/snow is 0.200. She coasts for a distance of 10.4 m before coming to the edge of a cliff. Without slowing down...

Homework Statement An airplane flies at an air speed of 300 miles per hour, in the direction toward southwest. There is a head wind of 75 mi/hr in the direction toward due east. (A) Determine the ground speed. (B) Determine the direction of motion of the plane, expressed as an angle...

Homework Statement Two points P and Q have position vectors in a reference frame that are given by rOP = 50ti and rOQ = 40i - 20tj meters. Find the minimum distance between P and Q and the time at which this occurs. Homework Equations The Attempt at a Solution I suppose I take the...

A ball is thrown downwards from a top of a 20m building with an initial velocity of 15m/s. What equation could be used to model its height? My answer: h (t) = -4.9t2-15t+20

Homework Statement Block A weighs 75lbf and the coefficients of static and kinematic friction between A and the plane are both 0.50. Determine the acceleration of A under the action of the 25 lbf force when the velocity at A is (a) 8fps up the plane, (b) 15 fps down the plane. (c) Zero...

Homework Statement I am unable to solve part b and please help me check whether is there anything wrong with my graph..:redface:The Attempt at a Solution Segment A Vi=0 V=3 S=60 a=9.81 v=vi+at 3=0+9.8(t) t=0.305s Segment B Vi=3 V=0 a=-2 v=vi+at 0=3-2t t=1 t=1+0.305=wrong answer :cry:

Homework Statement I cannot get the answer for part c, -13.02rad/s^2 The Attempt at a Solution 52.08=260.42+α(10) -208.34=10α α= -20.83rad/s^2 (Correct) 0=52.08+α(10) -52.08=10α α=-5.208rad/s^2 (Wrong) Please help, thanks..

Homework Statement Since Gear A -------- Vi=0 t=12s θ=40∏ as given in the question, can I assume that Vi=0 t=12s for Gear B/Drum C as well? If not why? Thanks..

Homework Statement The uniform 3.6m pole is hinged to the truck bed and released from the vertical position as the truck starts from rest with than acceleration of 0.9m/s^2. If the acceleration remains constant during the motion of the pole, calculate the angular velocity of the pole as it...

Homework Statement "A race car driver must average 180 km/h for 4 laps to qualify for a race. Because of engine trouble, the car averages only 150 km/h over the first 2 laps. What speed must be maintained for the last 2 laps?" Homework Equations The Attempt at a Solution So I do...

As part of a culminating activity for my course, I am asked to design and build a toy for children that uses kinematics and conservation of energy. I was wondering if anybody could post some ideas?

Homework Statement A car is behind a truck going 25 m/s on the highway. The car's driver looks for an oportunity to pass, guessing that his car can accelerate at 1.0 m/s^2. He gauges that he has to cover the 20 m length of the truck, plus 10 m clear room at the rear of the truck and 10 m at the...

Usually these problems are really simple for me, but this one is making me lose my mind: "An archer wishes to shoot an arrow at a target at eye level a distance of 49.0 m away. If the initial speed imparted to the arrow is 69.3 m/s, what angle should the arrow make with the horizontal as it is...

Homework Statement A truck accelerates uniformly from rest to 48km/h in 20s, holds speed for 2 minutes, and then accelerates to 100km/h at a rate of 17m/s^2. How long does it take, from rest, to reach 100km/h and what distance it traveled in this time? The book says it takes 148.5s, and I...

Homework Statement See attached picture please. It is supposed to be a pully system with 100N being applied upwards and i need to prove the values given in the diagram i drew and my teacher gave me it as a question to do since we have finished the scottish higher course. Homework Equations...

Homework Statement http://img62.imageshack.us/img62/6705/smallproj.jpg The Attempt at a Solution Basically I'm struggling to understand what am I supposed to differentiate. If it's V, which is 60, then the derivative of a number is zero. If it's a, then, a = -1.2v2 If I am...

Question 7 a) Acceleration is the rate of change of velocity Use your definition in (a) to show that v = u + at, where v is the final velocity, u is the initial velocity and a and t are the acceleration and the time interval respectively. State the conditions that must be satisfied for...

1)A rock is dropped off a cliff and falls the first half of the distance into the ground in t1 seconds. If it falls the second half of the distance in t2 seconds, what is the value of t2/t1? Relevant equations: I think the kinematics equations of d=vt+(1/2)at^2 I have no idea how to solve...

Homework Statement A stone is dropped from the top of a tower of height 40 m. The stone falls from rest and air resistance is negligible. What time is taken for the stone to fall the last 10m to the ground? A 0.38s B 1.4s C 2.5s D 2.9s Homework Equations The Attempt at a...

Homework Statement Problem 15.18: I've defined the positive J (fixed) axis along the pole pointing upwards and the positive X (fixed) axis going to the right, with both centered at the point of contact between the hoop and the pole, which I will refer to as point O. The rotating axes...

Homework Statement Displacement of a particle moving in a straight line is s= 6 + 12t - 2t^2 find the distance traveled till t=5. Homework Equations firstly i am having confusion in correctly interpreting the equation. The equation gives us the displacement in 't' th...

Homework Statement using a map, measure the displacement from Bradford to Milton. Compare the distances traveled to the for each route above with this displacement and explain the differences Homework Equations Δd = vΔt The Attempt at a Solution okay, so i may just being having a brain fart...

Homework Statement Base ball player makes perfect contact with a ball striking it at 45° angle above the horizontal at a point 1.3 m above the ground. His ball just makes it clear of the 3m wall 130m from home plate. What was the velocity at with he struck the ball. Homework Equations is...

Kinematics -- marbles rolling down a ramp and into sand Homework Statement 14) The student carries out an experiment to investigate momentum and collisions. A ball bearing is rolled down a ramp clamped at the edge of a bench. The ball bearing makes a head-on collision with a marble at the...

Homework Statement A wheel starts from rest and accelerates uniformly to 200rpm in 6s. After it has been rotating for some time at this speed, the brakes are applied and it takes 5 minutes to stop the wheel. If the total number of revolutions is 3100, calculate the total time of rotation...

Homework Statement A speeder zooms past a parked police car at a constant speed of 70 mph. Then, 3 sec later, the policewoman starts accelerating from rest at 10 ft/s^2 until her velocity is 85 mph. How long does it take her to overtake the speeding car if it neither slows down nor speeds...

Homework Statement Jack is driving with a pail of water along a straight pathway at a steady 25 m/s when he passes Jill who is parked in her minivan waiting for him. When Jack is beside Jill, she begins accelerating at the rate of 4.0 x 10-3 m/s2 in the same direction that Jack is driving...

Please forgive me if the answer to this question is obvious, I studied Political Science for three years in undergrad before I realized 'real' science was far more rewarding. My question (not homework): I understand that Work-Energy can be used for projectile motion, if what you're after is...

Homework Statement at the instant the traffic light turns green, an auto mobile starts with a constant acceleration of 2.2 m/s^2. At the same instant, a truck traveling with a constant speed of 9.5 m/s overtakes and passes the car. a) how far beyond the traffic signal will the auto mobile...

Homework Statement A point Q in rectilinear motion passes through the origin at t=0, and from then until 5 seconds have passed, the acceleration of Q is 6 ft/s^2 to the right. Beginning at t = 5s, the acceleration of Q is 12t ft/s^2 to the left. If after 2 more seconds point Q is 13 feet to...

Homework Statement Figure 2-21 shows a general situation in which a stream of people attempt to escape through an exit door that turns out to be locked. The people move toward the door at speed vs
3.50 m/s, are each d
0.25 m in depth, and are separated by L
1.75 m.The arrangement in...

1. A particle of mass m moves on the x-axis as follows. It starts from rest at t=0 from the point x=0 and comes to rest at t=1 at the point x=1. No other information is available about its motion at intermediate times (0<t<1). If α denotes the instantaneous acceleration of the particle, then...

Homework Statement So, our lab entails the students launching a projectile at a certain angle into a cup at a certain distance away. The launcher is 37 cm off of the ground and the cup is 7cm of the ground, so the Dy = 37-7 = 30cm. We will be given the angle in class and will be asked to...

Homework Statement A one stage booster rocket has a Xo of 0m and a Vo of 0 m/s. The rocket takes off with a constant acceleration until 5 seconds when the boosters turn off and goes into free fall. The rocket is set to explode the instant it hits it's max height. The max height is 1200m...

Homework Statement A 5.0kg concrete block accelerates down a 34° slope at 4.2m/s^2. Find the coefficient of friction between the block and the slope. Homework Equations Fg=5*9.8=45 x=45sin30 y=45cos30 The Attempt at a Solution a=(mgsinθ-Ff)/m → Ff=mgsinθ-ma Thanks

Homework Statement Dr. Evil runs out to his car which is parked at the bottom of a hill that is inclined with the horizontal at 20(degrees) and blasts up the hill at an acceleration of 6 m/s2. James Bond runs out behind Dr. Evil to a mortar that is located conveniently exactly where Dr...

Homework Statement Emily and Grace are each in a bumper car facing each other 10m apart. Emily moves toward Grace at a constant speed of 2.5 m/s. Grace accelerates toward Emily at a rate of 0.5 m/s^2. Relative to where Emily started, where do the two bumper cars collide?Homework Equations...

Homework Statement A bird is coasting along in an easterly direction at 0.447 meters/sec when a strong wind from the south imparts a constant acceleration of 0.300 m/s2. If the acceleration from the wind lasts for 2.70 s, find the magnitude, r, and direction, θ, of the bird's displacement...

Check my "Throw the Ball" lab. (2D kinematics, force, work) Here I have a lab, with explanation, questions and my worked out answers (tried to make it as neat as possible with all the formulas I use, lowercase letters are subscript letters). Can someone carefully check my math for all this? I...

Kinematics Train Crash Question Homework Statement A passenger train is behind a freight train, both on the same set of tracks and moving in the same direction. The freight train is moving at a constant speed of 27. 0 m/s and maintains that speed. The passenger train is originally moving at...

Homework Statement A daredevil is shot out of a cannon at 33.7◦ to the horizontal with an initial speed of 25.5 m/s. A net is positioned at a horizontal distance of 43.7 m from the cannon from which the daredevil is shot. The acceleration of gravity is 9.81 m/s^2 At what height above the...

Homework Statement Hey guys, so here's the problem I'm given: You are watching an archery tournament when you start wondering how fast an arrow is shot from the bow. Remembering your physics, you ask one of the archers to shoot an arrow parallel to the ground. You find the arrow stuck in the...

Homework Statement In an emergency braking exercise, a student driver stops a car traveling at 83 km/h [W] in a time of 4.0 s. What is the car's acceleration during this time? Homework Equations The Attempt at a Solution a = (v2-v1)/t = 83/4 = 21 m/(s^2) [E]

Homework Statement A particle moves uniformly with speed v along the path y=kx^2 .Taking k as a positive constant, acceleration of the particle at x=0 is _________? Homework Equations options-a)2kv^2 b)kv^2 c)1/2(kv^2) d)2kv The Attempt at a Solution I did- y=kx^2...