Velocity of a box going up an inclined plane.

[Berean7]

Homework Statement

A box is hurled up an incline plane of 20 degrees at 10m/second. There is no friction. What is the velocity after 3 seconds. I know gravity and the sin of 20 degrees has to be factored in.

Homework Equations

v=u+at. u is initial velocity, v is velocity after 3 seconds, t is time.

The Attempt at a Solution

9.81x.342=3.355ms^-2. Using the above equation I calculate -.065m/s (10-3.55x3). This does not match any of my answers. I do not know were I went off-track.

 

[Fewmet]

Welcome to Physics Forums, Berean7.

I agree with your acceleration. I see that (10-3.55x3) is u+at, but were did that
-0.65 m/s come from?

 

[Chestermiller]

Homework Statement

A box is hurled up an incline plane of 20 degrees at 10m/second. There is no friction. What is the velocity after 3 seconds. I know gravity and the sin of 20 degrees has to be factored in.

Homework Equations

v=u+at. u is initial velocity, v is velocity after 3 seconds, t is time.

The Attempt at a Solution

9.81x.342=3.355ms^-2. Using the above equation I calculate -.065m/s (10-3.55x3). This does not match any of my answers. I do not know were I went off-track.

Check out the two numbers 3.355 and 3.55 in your analysis.

Chet

 

[Fewmet]

Good catch, Chet.

I should know better than to answer questions after hours of grading final exams...

 

[Berean7]

Thank you 4 the replies. .355 should have been used in both spots. I just typed it wrong. I arrived at the right answer.