An ice sled powered by a rocket engine starts from rest on a large frozen lake and accelerates at +13.0 m/s². At t1 the rocket engine is shut down and the sled moves with constant velocity v until t2. The total distance traveled by the sled is 5.30 à 103 m and the total time is 90.0 s. Find t1, t2, and v.

Respuesta :

Answer:

The value of t₁ is 4.65 sec.

The value of t₂ is 85.35 sec.

The value of v is 60.45 m/s.

Explanation:

Given that,

Acceleration = 13.0 m/s²

Total distance [tex]d=5.30\times10^{3}\ m[/tex]

Total time T=90.0 sec

We need to calculate the distance

Using equation of motion

[tex]s_{1}=ut+\dfrac{1}{2}at^2[/tex]

Put the value into the formula

[tex]s_{1}=0+\dfrac{1}{2}\times13\times (t_{1})^2[/tex]....(I)

We need to calculate the second distance

Using formula of distance

[tex]s_{2}=vt[/tex]

Put the value into the formula

[tex]s_{2}=vt_{2}[/tex]....(II)

We need to calculate the velocity

Using equation of motion

[tex]v=ut+at[/tex]

Put the value into the formula

[tex]v=13t_{1}[/tex]....(III)

Put the value of v in equation (II)

[tex]s_{2}=13t_{1}t_{2}[/tex]

Now, on addition equation (I) and equation (III)

[tex]s_{1}+s_{2}=\dfrac{1}{2}\times13\times (t_{1})^2+13t_{1}t_{2}[/tex]

Put the value into the formula

[tex]5.30\times10^{3}=\dfrac{1}{2}\times13\times (t_{1})^2+13t_{1}t_{2}[/tex]

[tex]5.30\times10^{3}=\dfrac{1}{2}\times13\times (t_{1})^2+13t_{1}(90-t_{1})[/tex]

[tex]5.30\times10^{3}=\dfrac{1}{2}\times13\times (t_{1})^2+13t_{1}\times90-13(t_{1})^2[/tex]

[tex]6.5t_{1}^2-1170t_{1}+5.30\times10^{3}=0[/tex]

[tex]t_{1}=4.65\ sec[/tex]

Put the value in the equation (I)

[tex]s_{1}=0+\dfrac{1}{2}\times13\times (4.65)^2[/tex]

[tex]s_{1}=140.54\ m[/tex]

Now the value of [tex]t_{2}[/tex] is

[tex]t_{1}+t_{2}=90[/tex]

Put the value of t₁

[tex]t_{2}=90-4.65[/tex]

[tex]t_{2}=85.35\ sec[/tex]

The value of velocity is

Put the value in the equation (III)

[tex]v=13\times4.65[/tex]

[tex]v=60.45\ m/s[/tex]

The value of [tex]s_{2}[/tex]

Put the value of v and t₁ in equation (II)

[tex]s_{2}=vt_{1}[/tex]

[tex]s_{2}=60.45\times4.65[/tex]

[tex]s_{2}=281.1\ m[/tex]

Hence, The value of t₁ is 4.65 sec.

The value of t₂ is 85.35 sec.

The value of v is 60.45 m/s.