Answer:
False.
Explanation:
If you throw a ball into the air, Earth exerts a force on the ball. Also, the ball in the air exerts a force on Earth.
This ultimately implies that, there is a force pair between the earth and the ball.
Mirrors don't cause refraction.
A convex mirror could cause parallel rays to REFLECT away from each other.
Answer:
60 m/s
Explanation:
From the law of conservation of energy,
The kinetic energy of the plane = Energy of store in the spring when the plane lands.
1/2mv² = 1/2ke²
making v the subject of the equation.
v = √(ke²/m).................... Equation 1
Where v = the plane landing speed, k = spring constant, e = extension. m = mass of the plane.
Given: m = 15000 kg, k = 60000 N/m, e = 30 m.
Substitute into equation 1
v = √(60000×30²/15000)
v = √(4×900)
v = √(3600)
v = 60 m/s.
Hence the plane's landing speed = 60 m/s
