A 2,100 kg car is lifted by a pulley. If the cable breaks at 4.50 m, what is the velocity of the car when it hits the ground?

Question

anonymous · Answer

@thomaster

amistre64 · Answer

looks like we might be able to use kinetic energy equation

anonymous · Answer

What is that equation.?

amistre64 · Answer

$$KE=\frac12mv^2$$

amistre64 · Answer

since its hit the ground then KE = PE$$PE=mgh$$

amistre64 · Answer

so..$$mgh=\frac{1}{2}mv^2$$
$$2gh=v^2$$
finish solving for v

amistre64 · Answer

there is another route we could take, but this ones fair enough

anonymous · Answer

Im not sure if i did it right but I got 88.2

amistre64 · Answer

lets verify

sqrt(2(9.8)(4.5)) ... you didnt sqrt it

anonymous · Answer

So it would be 9.39 right?

anonymous · Answer

and the units would be m/s

amistre64 · Answer

another method is simply to use the formula:$$s=\frac12at^2+v_ot+h_o$$and solve for t to determine the solution to:$$v=at+v_o$$
-----------------------------
$$0=-\frac12(9.8)t^2+4.5$$
$$9=9.8t^2$$
$$\sqrt{\frac{9}{9.8}}=t$$
$$v=9.8\sqrt{\frac{9}{9.8}}$$
$$v=\sqrt{9(9.8)}$$
$$v=\sqrt{2(4.5)(9.8)}$$
yay its the same

amistre64 · Answer

yes, 9.39 m/s

anonymous · Answer

Okay :D thank you and are you good at refraction?

amistre64 · Answer

i dont have any experience with refraction so prolly not

anonymous · Answer

Hmm okay well thank you :D

amistre64 · Answer

youre welcome, and good luck :)