Find the total time taken and acceleration in the given problem-Kinematics

[chwala]

Homework Statement

Kindly see attached; interest only on parts;

a, c and d

Relevant Equations

Kinematics equations

This is the question; I made some math error...then i just realised this is an easy problem...anyway, i know you guys may have an alternative approach to this; kindly share...

For part (a) i have;

$a=\dfrac{10}{t_1}$ and $2a=\dfrac{20-10}{(t_1+t_2)-t_1}$

$⇒\dfrac{10}{t_1}=\dfrac{10}{2t_2}$

$t_1=2t_2$

For part (c); i have

$A_{total}= A_1+A_2+A_3$

where

$A_1=\dfrac{1}{2} × t_1 × 10$

$A_2=\dfrac{1}{2} × t_2 × (20+10)$

$A_3= 24 × 20$

$555=10t_2+15t_2+480$

$75=25t_2$

$t_2=3$ seconds

$t_{total}=6+3+24=33$seconds

For part (d),

$a=\dfrac{10}{3}=3\frac{1}{3} m/s^2$

Cheers! Bingo!

 

[SammyS]

Homework Statement:: Kindly see attached; interest only on parts;

a, c and d
Relevant Equations:: Kinematics equations

This is the question; I made some math error...then i just realised this is an easy problem...anyway, i know you guys may have an alternative approach to this; kindly share...

View attachment 321883For part (a) i have;

$a=\dfrac{10}{t_1}$ and $2a=\dfrac{20-10}{(t_1+t_2)-t_1}$

$⇒\dfrac{10}{t_1}=\dfrac{10}{2t_2}$

$t_1=2t_2$

For part (c); i have

$A_{total}= A_1+A_2+A_3$

where

$A_1=\dfrac{1}{2} × t_1 × 10$

$A_2=\dfrac{1}{2} × t_2 × (20+10)$

$A_3= 24 × 20$

$555=10t_2+15t_2+480$

$75=25t_2$

$t_2=3$ seconds

$t_{total}=6+3+24=33$seconds

For part (d),

$a=\dfrac{10}{3}=3\frac{1}{3} m/s^2$

Cheers! Bingo!

Yes, there does appear to be some math error.

I see that you skipped part (b), but the title of the thread,

"Solve the given problem involving the velocity-time graph",

does promise a graph.

 

[chwala]

Yes, there does appear to be some math error.

I see that you skipped part (b), but the title of the thread,

"Solve the given problem involving the velocity-time graph",

does promise a graph.

part (b) is fine with me...i was interested on the highlighted part. I amended the thread title...

Cheers @SammyS

 

[MatinSAR]

part (b) is fine with me...i was interested on the highlighted part. I amended the thread title...

Cheers @SammyS

I agree with a and c.
But I think in part d you've made a mistake.
You said a=10/t1 so a should be equal to 10/6.