Answer:

Explanation:
Δ
- Δ
is the difference in velocity before and after a given time.
is the acceleration of the object during this time.
is time
is another way to write this equation.
- The Δ symbol represents "the difference between the initial and final values of a magnitude or vector", so Δ


- I rearranged this equation to solve for
, but this is a step that you don't need to take, it's just good to get in the habit of doing this. - Plug in the given values. Note that our final velocity is
, because the car travels until at <em>rest</em>.
![a=\frac{v_f-v_i}{t}\\a=\frac{(0)-[(17.1\frac{miles}{hour} )(\frac{hour}{3600s})(\frac{1609.34m}{mile})]}{9.7s}](https://tex.z-dn.net/?f=a%3D%5Cfrac%7Bv_f-v_i%7D%7Bt%7D%5C%5Ca%3D%5Cfrac%7B%280%29-%5B%2817.1%5Cfrac%7Bmiles%7D%7Bhour%7D%20%29%28%5Cfrac%7Bhour%7D%7B3600s%7D%29%28%5Cfrac%7B1609.34m%7D%7Bmile%7D%29%5D%7D%7B9.7s%7D)
- Our initial velocity is in mph, something not in standard units, so if not changed, you will get an incorrect answer. What you need to do is cancel out the units your prior value had using division and multiplication, and at the same time multiply and divide the correct numbers and units into your equation. Or look up a converter.
![a=\frac{(0)-[(17.1\frac{miles}{hour} )(\frac{hour}{3600s})(\frac{1609.34m}{mile})]}{9.7s}\\a=\frac{0m/s-7.6m/s}{9.7s} \\a=\frac{-7.6m/s}{9.7s}](https://tex.z-dn.net/?f=a%3D%5Cfrac%7B%280%29-%5B%2817.1%5Cfrac%7Bmiles%7D%7Bhour%7D%20%29%28%5Cfrac%7Bhour%7D%7B3600s%7D%29%28%5Cfrac%7B1609.34m%7D%7Bmile%7D%29%5D%7D%7B9.7s%7D%5C%5Ca%3D%5Cfrac%7B0m%2Fs-7.6m%2Fs%7D%7B9.7s%7D%20%5C%5Ca%3D%5Cfrac%7B-7.6m%2Fs%7D%7B9.7s%7D)
- if you converted correctly, your answer for
will be ≅
. - Now divide. Notice that the units for acceleration are
or <em>meters per second, per second</em>.

- Our final answer is <em>negative </em>because the car is <em>slowing down</em>. Do not square this answer as the square symbol only applies to the units, not the magnitude.
Answer: C. -12 newtons
Explanation: Since, the block is in static equilibrium,
the net force on the block is zero i.e. balance forces are acting on the block.
In the horizontal direction,
force applied+force due to friction = 0
20 N + (-20N) = 0
In the vertical direction as well, net force is zero:
Force due to gravity + force exerted by the ground = 0
12 N + force exerted by the ground = 0
⇒force exerted by the ground = 0 -12 N = -12 N
Thus, the correct option is C. -12 N where negative sign means that the direction of the force due to ground is opposite to the force of gravity.
Answer:
15.9 m
Explanation:
Use the equation for gravitational potential energy (Ug):
Ug= mass*g*height
250,000 J= 1600 kg*9.8 m/s^2*height
height= 15.9 m
Hope this helps!!! :)