Answer:
300 m
Explanation:
The train accelerate from the rest so u = 0 m/sec
Final speed that is v = 80 m/sec
Time t = 30 sec
The distance traveled by first plane = 1200 m
We know the equation of motion 
where s is distance a is acceleration and u is initial velocity
Using this equation for first plane 
As the acceleration is same for both the plane so a for second plane will be 2.67 
The another equation of motion is 
using this equation for second plane 
s = 300 m
Answer: 6.9x 107 in standard form is 69,000,000
Answer:
The correct answer is B
Explanation:
Let's calculate the electric field using Gauss's law, which states that the electric field flow is equal to the charge faced by the dielectric permittivity
Φ
= ∫ E. dA = 
/ ε₀
For this case we create a Gaussian surface that is a sphere. We can see that the two of the sphere and the field lines from the spherical shell grant in the direction whereby the scalar product is reduced to the ordinary product
∫ E dA = / ε₀
The area of a sphere is
A = 4π r²
E 4π r² = / ε₀
E = (1 /4πε₀
) q / r²
Having the solution of the problem let's analyze the points:
A ) r = 3R / 4 = 0.75 R.
In this case there is no charge inside the Gaussian surface therefore the electric field is zero
E = 0
B) r = 5R / 4 = 1.25R
In this case the entire charge is inside the Gaussian surface, the field is
E = (1 /4πε₀
) Q / (1.25R)²
E = (1 /4πε₀
) Q / R2 1 / 1.56²
E₀ = (1 /4π ε₀
) Q / R²
= Eo /1.56
²
= 0.41 Eo
C) r = 2R
All charge inside is inside the Gaussian surface
=(1 /4π ε₀
) Q 1/(2R)²
= (1 /4π ε₀
) q/R² 1/4
= Eo 1/4
= 0.25 Eo
D) False the field changes with distance
The correct answer is B
Answer:
A. kinetic energy
B. angular velocity
E. angular position
Explanation:
The quantities that cannot be constant if a constant net torque is exerted on an objecta are:
A. Kinetic energy. If a torque is applied, the linear or angular speed will be changing at a rate proportional to the torque, so the kinetic energy will change too.
B. Angular velocity. It will change at a rate equal to the torque.
C. Angular position. If the angular velocity changes, the angular position will change.
as well.
1. Correct
Explanation
An inclined plane is a flat surface which lie at an angle, Its one end is higher than the other this inclined plane is used as an aid for raising or lowering a load. Staircase also work in similar manner
2. Correct
Explanation
yes all simple machine have a fulcrum
3. Incorrect
Explanation
when we swim that time our arms and legs 'push' the water due to which water displaced in backward direction so her we applied a positive work on the water. According to Newton's Third Law,same magnitude of work is done by water in opposite direction to push us back on our arms and legs. therefore water also does positive work on us.
4. incorrect
Explanation
The force exerted by a machine on an object is input force
5. Incorrect
Explanation
when the input force is greater than the output force that time machine have mechanical advantage of less than 1.
