Finding speed of a falling brick using distance and the acceleration of gravity

AI Thread Summary
The discussion centers on calculating the speed of a falling brick after it has dropped 30 meters under the acceleration of gravity at 10 m/s². The initial calculation of speed as 10 m/s is incorrect, as it confuses average speed with instantaneous speed. Participants emphasize the importance of the SUVAT equations for solving such physics problems. The original poster expresses confusion but later acknowledges understanding after receiving guidance on these equations. The conversation concludes with a positive note of gratitude for the assistance provided.
vytrx
Messages
4
Reaction score
3
Homework Statement
A supervisor 1.8m tall visits a construction site a brick resting at the edge of a roof 50m above the ground suddenly falls at the instant when the brick has fallen 30m without encountering any air resistance, the supervisor sees the brick coming down directly towards him from above as shown in the following figure. (attached) Calculate the speed of the brick after it has falled 30 m from the roof
Relevant Equations
Speed=distance/time
acceleration of gravity is 10m/s^2
Since the brick has fallen 30m and the acceleration of gravity is 10m/s^2 the brick would have fallen 3 seconds speed of brick would then be 30/3 leaving the answer at 10m/s?I am new to physics and this question has left me stumped
 

Attachments

  • 1651731802651.jpg
    1651731802651.jpg
    21.5 KB · Views: 164
Physics news on Phys.org
vytrx said:
Relevant Equations:: Speed=distance/time
That's only true for constant speed. Or, in simple cases, for calculating the average speed.

Do you know the SUVAT equations?

vytrx said:
Since the brick has fallen 30m and the acceleration of gravity is 10m/s^2 the brick would have fallen 3 seconds
You may be confusing speed and acceleration here.
vytrx said:
speed of brick would then be 30/3 leaving the answer at 10m/s?
This is not correct.

:welcome:
 
PeroK said:
That's only true for constant speed. Or, in simple cases, for calculating the average speed.

Do you know the SUVAT equations?You may be confusing speed and acceleration here.

This is not correct.

:welcome:
No I'm not familiar with the SUVAT equations, yes I may be confusing the two would you care to explain how this question is done? I've asked one of my friends that said that the answer was 24.5 but I'm not entirely sure how to get there
 
vytrx said:
No I'm not familiar with the SUVAT equations, yes I may be confusing the two would you care to explain how this question is done? I've asked one of my friends that said that the answer was 24.5 but I'm not entirely sure how to get there
The SUVAT equations are the starting point for a study of physics, so you'll need to learn about them. Try this to get you started.

https://www.ncl.ac.uk/webtemplate/a...mechanics/kinematics/equations-of-motion.html
 
  • Like
Likes Grelbr42 and Lnewqban
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Trying to understand the logic behind adding vectors with an angle between them'
My initial calculation was to subtract V1 from V2 to show that from the perspective of the second aircraft the first one is -300km/h. So i checked with ChatGPT and it said I cant just subtract them because I have an angle between them. So I dont understand the reasoning of it. Like why should a velocity be dependent on an angle? I was thinking about how it would look like if the planes where parallel to each other, and then how it look like if one is turning away and I dont see it. Since...
Back
Top