Question

Givens T (N) m (kg) Viy (m/s) ry (m) 78 20 Scenario 1 Scenario 2 Trn A. What is the weight of the object? S1. S2. B. What is ay? S1. S2 C. what is rfv when t = 4 s? S1. S2 woll D. What is vjy when t 4 s? S1 S2.

Answer 1

[A] In all the questions I'll take g=10

Weight is same in both situations.

$W=mg=80\textup{ N}$

[B]

S1

$T-mg=ma_y$

$a_y=T/m-g=-0.25\textup{ m/s}^2$

which means the block is moving down.

S2

I'll assume downward this time.

$mg-T\cos45\degree=ma_y$

$a_y=g-\frac{T}{m}\cos45\degree=3.1\textup{ m/s}^2$

[C]

We already calculated the net downwards acceleration

S1

Use the following, for initial velocity 0,

$r_{fy}=r_{iy}+\frac{1}{2}a_yt^2$

$r_{fy}=20-\frac{1}{2}\times0.25\times4^2=18\textup{ m}$

S2

Similarly, here

$r_{fy}=20-\frac{1}{2}\times3.1\times4^2=-4.85\textup{ m}$

[D]

For velocity

$v_{fy}=v_{iy}+a_yt$

S1

$v_{fy}=0-0.25\times 4=-1\textup{ m/s}$

S2

$v_{fy}=0-3.1\times 4=-12.4\textup{ m/s}$