Kinematics: Solving Questions on Speed, Distance, Time & Acceleration

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Homework Help Overview

The discussion revolves around kinematics, specifically focusing on problems involving speed, distance, time, and acceleration. Participants are addressing various scenarios, including a stone thrown from a cliff and a car rolling off a vertical edge.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss setting up equations of motion for the problems. Some express difficulty in solving the first problem, while others share their calculated answers and seek validation. There are questions regarding the correctness of the results and the assumptions made in the calculations.

Discussion Status

The discussion is active, with participants sharing their attempts and results. Some have provided specific numerical answers, while others are questioning the validity of their calculations and seeking feedback. There is no explicit consensus on the correctness of the answers, and multiple interpretations of the problems are being explored.

Contextual Notes

Participants are working under the constraints of homework rules, which may limit the information they can share or the methods they can use. There are indications of missing variables and assumptions that are being debated in the context of the problems presented.

jimlee4262
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1.A stone is thrown vertically upward with a speed of 11.0 m/s from the edge of a cliff 79.0 m high (Fig. 2-32).

(a) How much later does it reach the bottom of the cliff?

(b) What is its speed just before hitting?

(c) What total distance did it travel?

2.If a car rolls gently (v0 = 0) off a vertical cliff, how long does it take it to reach 74 km/h?

3.A sports car accelerates from rest to 99 km/h in 6.2 s. What is its average acceleration in m/s2?
 
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Most of these can be solved once you set up an equation of motion representing your situation.

I suggest you make an attempt :o
 
yes i figured out the last two but the first one i am having trouble on... I found most of the missing variable but i can't seem to get the ones i need right.
 
the answers i have gotten for the first one is
A) 5.12
B)-39.3
C)-91.3
Can someone tell me if i did this wrong and help me
 
jimlee4262 said:
the answers i have gotten for the first one is
A) 5.12
B)-39.3
C)-91.3
Can someone tell me if i did this wrong and help me

a) 0.13424051
b)588.495976
s)79.0
 
the pro said:
a) 0.13424051
b)588.495976
s)79.0

a) 0.13424051s doesn't leave much time to reach the maximum height and then fall 79m plus the additional height achieved by the 11.0m/s initial velocity.
b) Accelerating to 588.495976m/s in 0.13424051s would require that acceleration due to the force of gravity is 4380.1979 m/s2
c) What about the distance upward due to the initial velocity of 11.0m/s?
 
I came up with
a) 5.29 s
b) 40.9 m/s (the problem asks for speed, which is the absolute value of velocity)
c) 91.4 m
 

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