Answer:
a) 
b) 
c) 
Explanation:
<em><u>The knowable variables are </u></em>




Since the three traffic signs are <u>equally spaced</u>, the <u>distance between each sign is
</u>
a) 
b) 
Since we know the velocity in two points and the time the car takes to pass the traffic signs
c) 
Answer:
B) Friction
Explanation:
The main source of error is the omission of the effect from friction between block and incline, which is directly proportional to the mass of the block. The force of gravity is constant. The friction force dissipates part of the gravitational potential energy, generating a final speed less than calculated under the consideration of a conservative system. Air resistance is neglected at low speeds like this case.
We are given: Final velocity (
)=20 m/s .
Time t= 2.51 s and
distance s = 82.9 m.
We know, equation of motion

Let us plug values of final velocity, and time in above equation.


Subtracting 2.51a from both sides, we get
-----------equation(1)
Using another equation of motion

Plugging values of vi =20-2.51a, t=2.51 and distnace s=82.9 in this equation.
We get,

Now, we need to solve it for a.
20-20+2.51a=165.8a.
-163.29a=0
a=0.
So, the acceleration would be 0 m/s^2.
Answer:
I = 4.75 A
Explanation:
To find the current in the wire you use the following relation:
(1)
E: electric field E(t)=0.0004t2−0.0001t+0.0004
ρ: resistivity of the material = 2.75×10−8 ohm-meters
J: current density
The current density is also given by:
(2)
I: current
A: cross area of the wire = π(d/2)^2
d: diameter of the wire = 0.205 cm = 0.00205 m
You replace the equation (2) into the equation (1), and you solve for the current I:

Next, you replace for all variables:

hence, the current in the wire is 4.75A
Answer:
Explanation:
Impulse = change in momentum
mv - mu , v and u are final and initial velocity during impact at surface
For downward motion of baseball
v² = u² + 2gh₁
= 2 x 9.8 x 2.25
v = 6.64 m / s
It becomes initial velocity during impact .
For body going upwards
v² = u² - 2gh₂
u² = 2 x 9.8 x 1.38
u = 5.2 m / s
This becomes final velocity after impact
change in momentum
m ( final velocity - initial velocity )
.49 ( 5.2 - 6.64 )
= .7056 N.s.
Impulse by floor in upward direction
= .7056 N.s