because a chemical change takes time
Answer:
The average speed of a car is 20 km/h.
Explanation:
We have,
Distance covered by car is 10 km
Time taken by the car to cover that distance is 30 min. 30 min means 0.5 hours.
It is required to find the average speed of a car. It can be calculated using formula of average speed which is given by :
So, the average speed of a car is 20 km/h.
Answer:
a = (v₃₂ - v₂₁) / (t₃₂ -t₂₁)
Explanation:
This is an exercise of average speed, which is defined with the variation of the distance in the unit of time
v = (y₃ - y₂) / (t₃-t₂)
the midpoint of a magnitude is the sum of the magnitude between 2
t_mid = (t₂ + t₃) / 2
the same reasoning is used for the mean acceleration
a = (v_f - v₀) / (t_f - t₀)
in our case
a = (v₃₂ - v₂₁) / (t₃₂ -t₂₁)
Answer:
Therefore, the answer is E. They strike the plane at the same time.
Explanation:
Here, it is seen that the time depends only on acceleration due to gravity (which is a constant) and vertical displacement, and not on velocity of the bullets or mass of the bullets.
Hence, the bullets that are fired simultaneously parallel to the horizontal plane will strike the plane at the same time.
using equation of motion for displacement
s= ut + ¹/₂gt²
here, g is the acceleration due to gravity along y- direction
U along y is 0
s = (0)t + ¹/₂gt²
s=¹/₂gt²
make t the subject of formula = 
Answer:
v = 1.98*10^8 m/s
Explanation:
Given:
- Rod at rest in S' frame
- makes an angle Q = sin^-1 (3/5) in reference frame S'
- makes an angle of 45 degree in frame S
Find:
What must be the value of v if as measured in S the rod is at a 45 degree)
Solution:
- In reference frame S'
x' component = L*cos(Q)
y' component = L*sin(Q)
- Apply length contraction to convert projected S' frame lengths to S frame:
x component = L*cos(Q) / γ (Length contraction)
y component = L*sin(Q) (No motion)
- If the rod is at angle 45° to the x axis, as measured in F, then the x and y components must be equal:
L*sin(Q) = L*cos(Q) / γ
Given: γ = c / sqrt(c^2 - v^2)
c / sqrt(c^2 - v^2) = cot(Q)
1 - (v/c)^2 = tan(Q)
v = c*sqrt( 1 - tan^2 (Q))
For the case when Q = sin^-1 (3/5)::
tan(Q) = 3/4
v = c*sqrt( 1 - (3/4)^2)
v = c*sqrt(7) / 4 = 1.98*10^8 m/s
