Home » Posts tagged 'initial speed'

Tag Archives: initial speed

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Join 3,084 other subscribers

Archives

The problem of a rock thrown vertically up

A rock is thrown vertically upward from the ground with an initial speed 15m/s.

a. how high does it go
b. how much time is required for the rock to reach its maximum height?
c. what is the rock’s height at t=2.00s?

(Posted by Merhawi)

Answer:

(a)

u=15m/s

a=-10m/s2

v=0 m/s (at the max height)

S=?

v2-u2=2aS

S=v2-u2/2a

=225/20

=11.25 m

(b) From the above case

using v=u+at

t=v-u/a=1.5s

(c) Use S = ut + 1/2 at2

put t=2s, u = 15m/s, a=-10m/s2

S=30 – 20 = 10 m

(If you use g = 9.8 m/s2 The answers will be slightly different)

A numerical from Projectile motion, friction and more

Hale asked:

One side of the roof of a building slopes up at 33.5°. A roofer kicks a round, flat rock that has been thrown onto the roof by a neighborhood child. The rock slides straight up the incline with an initial speed of 15.0 m/s. The coefficient of kinetic friction between the rock and the roof is 0.430. The rock slides 10.0 m up the roof to its peak. It crosses the ridge and goes into free fall, following a parabolic trajectory above the far side of the roof, with negligible air resistance. Determine the maximum height the rock reaches above the point where it was kicked.

(The question is left for visitors to answer.)

Ask a Doubt

Post your Physics Doubts here

Name (required)

Email (required)

Subject

Message/Doubt/Question

Upload a file if required

askphysics@Twitter

Half Yearly Exam Count Down

Half Yearly Exam Count Down KVS Ernakulam RegionOctober 17, 2017
The Half Yearly Examination for Kendriya Vidyalayas of Kerala starts from 17 October 2017
%d bloggers like this: