Answer:
a) a = -g = 9.8 m/s²
, b) a = 0 m/s² and c) t1 = 0.0213 s
Explanation:
a) At the moment the marble is released its velocity is zero, so it has no resistance force, the only force acting is its weight, so the acceleration is the acceleration of gravity
a = -g = 9.8 m / s²
b) When the marble goes its terminal velocity all forces have been equalized, therefore, the sum of them is zero and consequently if acceleration is also zero
a = 0 m / s²
c) We have to assume a specific type of resistive force, for liquid in general the resistive force is proportional to the speed of the body.
The expression of this situation is
v = mg / b (1 -
)
For a very long time the exponential is zero, so the terminal velocity is
= mg / b
b = mg /
b = 5 10-3 9.8 / 0.3
b = 0.163
We already have all the data to calculate the time for v = ½
½
=
(1 -
)
½ = 1- e (- 0.163 t1 / 5 10-3)
e (-32.6 t1) = 1-0.5 (by ln())
-32.6 t1 = ln 0.5
t1 = -1 / 32.6 (-0.693)
t1 = 0.0213 s
The doctor's average speed for the whole trip is 75 km per hour. His average velocity for the whole trip is zero.
Answer:
(a) 0.0178 Ω
(b) 3.4 A
(c) 6.4 x 10⁵ A/m²
(d) 9.01 x 10⁻³ V/m
Explanation:
(a)
σ = Electrical conductivity = 7.1 x 10⁷ Ω-m⁻¹
d = diameter of the wire = 2.6 mm = 2.6 x 10⁻³ m
Area of cross-section of the wire is given as
A = (0.25) π d²
A = (0.25) (3.14) (2.6 x 10⁻³)²
A = 5.3 x 10⁻⁶ m²
L = length of the wire = 6.7 m
Resistance of the wire is given as


R = 0.0178 Ω
(b)
V = potential drop across the ends of wire = 0.060 volts
i = current flowing in the wire
Using ohm's law, current flowing is given as


i = 3.4 A
(c)
Current density is given as


J = 6.4 x 10⁵ A/m²
(d)
Magnitude of electric field is given as


E = 9.01 x 10⁻³ V/m
Answer:
static friction acting opposite to the direction of travel
Explanation:
Because the Frictional force of the front wheels act to oppose the spinning, so, For the front wheels to roll without slipping, the friction must be static friction pointing in the direction of travel of the car.
Explanation: