Kinematics Definition and 1000 Threads

Homework Statement A commercial claims that a car can stop on a dime (17.9mm). If a car is initially traveling at 13.4m/s, what acceleration would the car experience coming to a stop in that short distance? Homework Equations avg acceleration Coversion The Attempt at a Solution I recognize...

Homework Statement A ball is traveling at 3m/s then bounces off of a tennis racket and returns at 2m/s. If the ball is in contact with the racket for 12ms, what is the average acceleration? Homework Equations average acceleration and conversion a=Vf-Vi/Tf-Ti 1s= 1000ms The Attempt at a...

Homework Statement A straight line is marked in meters in a field. A student begins at the zero position mark and ends at the 50 position mark. However, the student did not walk along the straight line. He uses a wheel that has a circumference of 1m and finds that it turns 100 times as he...

Homework Statement a) A ball is thrown in the -y direction off of a cliff with a velocity of 7m/s. If the ball takes 1.45s to reach the ground, how high off of the ground is the cliff? (Answer: -20m) Homework Equations Vf=Vi+a(t) Displacement=Vi(t)+1/2a(t)^2 Vf^2=Vi^2+2a(Displacement)...

We have a cube on an inclined plane. The tipping condition is the presence of an unbalanced torque relative to the center of mass (contributing forces are: the normal force and the force of friction). However, is this conditions equivalent to the previous one: The line of action of the force of...

Homework Statement To stop a car, first you require a certain reaction time to begin braking; then the car slows down under constant breaking decelaration. Suppose that the total distance moved by the car during these two phases is 56.7 m when its initial speed was 80.5 km/h and 24.4 m when its...

We have two identical balls sitting at the same height. One of them is released without applying any force (it falls freely) and the other one is given a non-zero horizontal velocity. Which of them will hit the ground first? The force of air resistance is proportional to the square of the...

Let's say that we have a bicycle wheel with radius $R = 25 cm$ and mass $m = 1 kg$. We spin the wheel in air so, that the tread is moving at the speed of $v_o = 50 km / h$. Then, we let it roll on asphalt, given the coefficient of static friction: $f_s = 0.9$ and kinetic friction: $f_k = 0.7$...

Homework Statement A man wishes to cross a river of width 120 m by a motorboat. His rowing speed in still water (or relative to water) is 3 m/s and his maximum walking speed is 1 m/s. The river flows with a velocity of 4 m/s. (a) Find the path which he should take to reach the point directly...

So, velocity is a vector, right? And vectors can't have negative magnitudes, right? Then why is leftward velocity considered negative in 1D kinematics? It just seems off to me. Same with acceleration, and pretty much _every vector in all of physics._

Question: A car accelerates from rest at a rate of 2.0m/s^2 [N]. What is the displacement of the car at t=15s? I tried (2m/s^2 [N])(15s)=30m/s [N] (30m/s [N])(15s) =450m [N] but guess wrong :( *Because the answer is 230m [N] How to solve this? anyone

Homework Statement Only (b) part[/B] Homework Equations time of flight= (2⋅u⋅sinθ)/g ---------------- - 1 total distance (range)= u⋅cosθ * time of flight (s=vt) =u⋅cosθ * (2⋅u⋅sinθ)/g...

Homework Statement 15.1 The airspeed of the plane is 200m/s, directed north. If the wind speed is 30m/s in the direction shown, determine the ground speed and the course (angle θ) of the plane. Homework Equations The Attempt at a Solution Is it so far correct the above? More questions...

Homework Statement Homework Equations xcxcxcxcxcxcxcxcxcxcxc[/B]The Attempt at a Solution My attempt: Let displacement of A be x m, Let displacement of B be y m, and Let displacement of C be z m. Step2: [/B]a+b+c+d=(a+x-y)+(b+x)+c+(d+z) 2x-y=-z Differentiating LHS and RHS components...

Homework Statement My problem is in integral calculus (I'm new to it). I know what it is and how it works (basically. I'm not too advanced right now). The problem is as following: (I will be posting comments/reasons along with what I've done and with what logic/understanding I've done it...

Hello, here's a derivation for one of the equations for Uniform Accelerated Motion (UAM). I like it because it's far more concise than the algebra version. Question though: is there any kind of meaningful interpretation of ds/dv (which starts everything off in step 1)? Thank you!

What does the slope/gradient of an acceleration-time graph indicate?

So, if kinematics is the study of motion without reference to its causes (which is how it seems to be defined in many places), then here is my attempt to come up with a complete picture of motion without reference to its causes. This is just a summary to help me organize my thoughts (it is NOT...

Homework Statement [/B] A particle P1 moves with a constant velocity v along x-axis, starting from origin. Another particle P2 chases particle P1 with constant speed v, starting from the point (0, d). Both motion begin simultaneously. Find - 1. Initial acceleration of P2. 2. Ultimate...

Hello, I'm reviewing kinematics for an upcoming AP physics exam, but I seem to have forgotten a crucial fact. In typical rocket problems (when the rocket blasts off with an initial acceleration for example 5 m/s^2), why don't we subtract 9.8 from 5m/s^2 when using a value for acceleration? When...

When the driver applies brakes its velocity starts decreasing and direction of acceleration will be same to the direction of velocity. Is this statement True of False? Please explain the true concept of this scenario. As far as I understand is that Velocity will start decreasing. But I am...

Imagine such situation: A bus is moving at constant speed, a man is standing on the bus and is not holding to anything - he is simply standing. Now, the bus starts breaking with constant negative acceleration and so the man will change his relative position due to the force of inertia. Now...

Homework Statement A block slides down a frictionless incline (30 degrees above horizontal) for L=1.4m until it meets a horizontal surface with coefficient of kinetic friction 0.3 before coming to rest. Use work and energy to find the distance that the block slides on the horizontal surface...

I understand that the centripetal force on an object of mass 'm' is (mv2)/r However, isn't this for an object going around in a circle? Suppose I have a curve (0.0033x2+−1.0038x+98.2331). What would be the fastest speed around this curve on the bounds x -> Please note that we would...

Homework Statement Homework Equations $$h=ut+1/2at^2$$ $$h=x\tan\theta-1/2g\frac{x^2}{u^2\cos^2\theta}$$ The Attempt at a Solution I tried to take a random angle theta for the lower particee and then using the equation of the upper particle tried to solve them together and find condition for...

Homework Statement A photon hits a proton at rest in the laboratory frame and there is the process: $$\gamma + p \rightarrow n+\pi^+$$ The mass of the pion is ##m_\pi## and assuming that the masses of the proton and the neutron are the same (##m##): Finding the threshold energy of the foton...

Homework Statement A particle moves in a straight line with the acceleration shown in the figure. Knowing that it starts from the origin with ##v_0 = -14ft/s##, plot the v-t and x-t curves for 0 < t < 15 s and determine (a) the maximum value of the velocity of the particle, (b) the maximum...

Homework Statement 11.9 The brakes of a car are applied, causing it to slow down at a rate of ##10 ft/s^2##. Knowing that the car stops in 300 ft, determine (a) how fast the car was traveling immediately before the brakes were applied, (b) the time required for the car to stop Homework...

Homework Statement A child of an Eskimo decided to slide down an igloo. The igloo looks like a hemisphere with radius R. When will the child fall off the slide? Homework Equations See belowThe Attempt at a Solution There are only two forces acting on the child - the force of gravity and the...

Homework Statement A loaded railroad car is rolling at a constant velocity when it couples with a spring and dashpot bumber system. After the coupling, the motion of the car is defined by the relation ##x = 60e^{-4.8t} sin16t##, where x and t are expressed in millimeters and seconds...

Homework Statement Starting from the center of a circular path of radius R, a particle P chases another particle Q that is moving with a uniform speed v on the circular path. The chaser P moves with a constant speed u and always remains collinear with the centre and location of the chased Q...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] Apologies for a bit hazy picture .Let the three particles be in a line after time 't' . If the inclined line (path of v) from the origin is perpendicular to the hypotenuse then we could write vt= v1cos45°t = v2cos45°t . But...

The situation: The mass is pushed up an incline with an angle of 1 degree with an initial velocity of 1 m/s, and it comes back down to its original position. The questions to answer: What is the total distance the object travels on the frictionless inclined plane? How long will the object...

Homework Statement Considering 2 scattering particles with momenta ##p_{1}, p_{2}##, where ##p_{2} = 0## in the Lab reference. The momenta of these 2 particles after elastic collision are ##p_{1}', p_{2}'##, respectively. Due to the 4-momentum relation, we have ##p_{1i}p_{1}^{'i} = e_{1}e_{1}'...

Homework Statement A person runs at a constant speed of 4.0 m/s to catch a stationary bus. When she is 6.0m behind it (t=0s), the bus leaves, accelerating with a (constant) acceleration of 1.2 m/s^2. How long does it take her to catch up to the bus? Homework Equations X = Xo + Vot + 0.5at^2...

Homework Statement Because of your technical background, you have been given a job as a student assistant in a university research laboratory that has been investigating possible accident-avoidance systems for oil tankers. Your group is concerned about oil spills in the North Atlantic caused by...

Homework Statement For each of the following cases, represent on the trajectory, the velocity and tangential and normal components of the acceleration at times t1 and t2 of a mobile that moves according to the graph of s (arc) versus t (time) on the left. The point O on the trajectory marks the...

Homework Statement [/B] An X-ray tube gives electrons constant acceleration over a distance of 14 cm . If their final speed is 1.0×107 m/s , what are the electrons' acceleration? Express your answer to two significant figures and include the appropriate units. Homework Equations My prof. has...

Homework Statement A plane is taking off from an airport directly west of the airport it wishes to touch down in. The plane in still air can travel with a constant speed of 730 km/h. If a wind is blowing constantly at 92 km/h [45° S of E], at what angle must the plane fly to compensate for the...

Hi everyone. I just have a very quick question regarding position time graphs and velocity time graphs for a pendulum. As we know, at the maximum displacement, the acceleration is at its maximum and the velocity is zero, and vice versa when the displacement is zero. When we put this...

Can anyone tell me the difference between concept of relative velocity and effective velocity and when to use the concept of relative velocity? For example, if a guy throws a ball from a moving object at an angle theta it undergoes projectile motion we write horizontal velocity as...

I’m trying to calculate how hard someone throws a ball. I know that F=ma, but the only force acting on a ball is the force of gravity and so the equation simply cancels out.

Currently design of turbomachinery (impellers/turbines) is more a form of art than an engineering process. One has to guess a bunch of parameters and check if they are right in much later stages of design. I was thinking about designing the other way: we know the initial and the final velocity...

Homework Statement Hi everyone, 8th grade physics teacher here. We are doing a handout where we have to identify time-velocity graphs with descriptions. Can you help me with this one? https://imgur.com/a/vEIkg A) The velocity is increasing at a uniform rate. B) The velocity is decreasing at...

Homework Statement l=2m b=1.5m The mass of the chair is 5kg. A boy with a mass of 50kg sits on the chair. The distance of the chair from the pole is 3m, and it spins around it horizontally with a radial velocity of 1.95 rad/s. The boy drops a ball at some moment, what would be its distance...

Homework Statement Suppose the acceleration of a particle is a function of x, where a(x)=(2.0 s-2)*x. (a) If the velocity is zero when x= 1.0 m, what is the speed when x=3.0 m? (b) How long does it take the particle to travel from x=1.0 m to x=3.0 m. a(x)=(2.0 s-2) * x (a) V(x=3) = ? , V(x=1)...

Homework Statement A circular plate with radius 0.5 m and mas 5 kg is hung on the wall, fixed at a point that is 0.3 m above its center. The plate can freely rotate about the fixed point with no friction. A very short-duration impulse of 5Ns, along a direction that is tangential to the...

Homework Statement Question: A circular cylinder with mass of 1 kg and radius a=0.1 m is rotating about its cylindrical axis at a rate of 5 revolutions per second. It is then placed on a flat surface. Assuming that there is no dissipation at contact and the cylinder is rolling without slipping...

Homework Statement Ball A is dropped from the top of a building of height h at the same instant that ball B is thrown vertically upward from the ground. At what height will the balls collide if the collision occurs when the balls are moving in the same direction and the speed of A is 4 times...

Homework Statement Object launched vertically with v initial =20 m/s. No air resistance. How long does it take to reach its max height? Homework Equations 1/2 at^2 + vot = dy .5mv^2=mgh The Attempt at a Solution I began by using conservation of energy to find the max height. .5mv^2 = mgh...