Trying to understand how to make Motion Diagrams

  • Thread starter Thread starter Dko
  • Start date Start date
  • Tags Tags
    Diagrams Motion
AI Thread Summary
The discussion focuses on understanding how to create Motion Diagrams for a physics homework problem involving a car's deceleration. The user is confused about the accuracy required in their diagrams and how to incorporate the driver's reaction time before braking. A suggestion is made to start by graphing the velocity over time, illustrating the initial speed and the subsequent deceleration. It is advised to first calculate the time it takes to decelerate from 35 m/s to 25 m/s, potentially simplifying the process by ignoring the reaction time initially. The user expresses that additional resources, like YouTube, have been helpful in clarifying their understanding.
Dko
Messages
9
Reaction score
0
Trying to do my first Physics home work assignment for college and I'm not really making any headway. He went thru the martial so fast while throwing in calculus that I'm not sure if I do or don't need.
My main problem with Motion Diagrams is I'm not sure how accurate I'm supposed to be and how do I get that level of accuracy I need?
The problem I'm on bellow, is really getting me because I don't know how to start. Should I show 35 meters of movement and the reaction time before the deceleration?

Homework Statement


"The driver of a car traveling at 35 m/s suddenly sees a police car. The driver attempts to reach the speed limit of 25 m/s by accelerating at 2.5 m/s^2. The driver has a reaction time of 0.55 s. (The reaction time is the time between first seeing the police car and pressing the brake.)

Homework Equations



The Attempt at a Solution


I really don't know how I would show a solution on here.

Hope my problem makes sense.
 
Physics news on Phys.org
Dko said:
Trying to do my first Physics home work assignment for college and I'm not really making any headway. He went thru the martial so fast while throwing in calculus that I'm not sure if I do or don't need.
My main problem with Motion Diagrams is I'm not sure how accurate I'm supposed to be and how do I get that level of accuracy I need?
The problem I'm on bellow, is really getting me because I don't know how to start. Should I show 35 meters of movement and the reaction time before the deceleration?

Homework Statement


"The driver of a car traveling at 35 m/s suddenly sees a police car. The driver attempts to reach the speed limit of 25 m/s by accelerating at 2.5 m/s^2. The driver has a reaction time of 0.55 s. (The reaction time is the time between first seeing the police car and pressing the brake.)

Homework Equations



The Attempt at a Solution


I really don't know how I would show a solution on here.

Hope my problem makes sense.

Welcome to the PF.

I would start this problem by drawing a graph with velocity on the vertical axis and time on the horizontal axis. Draw the 35m/s initial velocity starting before time t=0 (to the left of the vertical axis), and then at t=0, that's when he sees the police car. But there is reaction time before he starts decelerating, so the 35m/s line continues for a bit, and then starts decreasing due to the deceleration...
 
I recommend ignoring the reaction time of the driver and just starting by calculating how long it will take for the car to decelerate (or accelerate backwards) from 35 to 25 m/s with the acceleration given in the problem. Do you know how to do that?
edit: If you can do that then move on to berkeman said above.
 
Thanks. I think I have a handle on things now. Youtube helped some as well.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'Calculation of Tensile Forces in Piston-Type Water-Lifting Devices at Elevated Locations'
Figure 1 Overall Structure Diagram Figure 2: Top view of the piston when it is cylindrical A circular opening is created at a height of 5 meters above the water surface. Inside this opening is a sleeve-type piston with a cross-sectional area of 1 square meter. The piston is pulled to the right at a constant speed. The pulling force is(Figure 2): F = ρshg = 1000 × 1 × 5 × 10 = 50,000 N. Figure 3: Modifying the structure to incorporate a fixed internal piston When I modify the piston...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top