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# Physics/motion in straight line

Question
a particle moves in a straight line with a constant acceleration . it changes its velocity from 10 m/s to 20 m/s while passing through the distance 135 m in t second. the value of t is ?(option 1)9 2)10 3)1.8 4)12

Hello saroj,

I expect that you were given a set of 4 formulas often called parametric formulas or equations of motion. Some books may discuss them one at a time so they are not all on the same page. They are:

Vf = Vi + a*t
d = (Vi + Vf)*t/2
d = Vi*t + (1/2)*a*t^2
Vf^2 = Vi^2 + 2*a*d

Vf and Vi are final and initial velocity, a is acceleration, t is time, and d is distance. Most problems can be solved by choosing the appropriate formula. (But a carefully crafted question can force you to use 2 of them.) Look at the information you have and what you are asked for. You know Vi, Vf, and d. And you need to find t. Look at the 2nd of the formulas above. You know all the parameters in the formula, except t -- and t is what you need to find. Plug in the data and solve for t.

I hope this helps,
Steve
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Physics

Volunteer

#### Steve Johnson

##### Expertise

I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.

##### Experience

I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

Education/Credentials
BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University