There is no "why", because that's not what happens. The truth is
exactly the opposite.
Whatever the weight of a solid object is in air, that weight will appear
to be LESS when the object is immersed in water.
The object is lifted by a force equal to the weight of the fluid it displaces.
It displaces the same amount of air or water, and any amount of water
weighs more than the same amount of air. So the force that lifts the
object in water is greater than the force that lifts it in air, and the object
appears to weigh less in the water.
Answer:
It cancels recoil.
Explanation:
For each action there is an equal an opposite reaction.
The principle of conservation of momentum tell us that if a single spore were ejected the fern would suffer a recoil from it. This recoil would take energy and speed from the spore. But if they are ejected in pairs the recoil is canceled and all the energy is transferred to the spores resulting in higher speeds.
Answer:
t = 25.5 min
Explanation:
To know how many minutes does Richard save, you first calculate the time that Richard takes with both velocities v1 = 65mph and v2 = 80mph.
Next, you calculate the difference between both times t1 and t2:
This is the time that Richard saves when he drives with a speed of 80mph. Finally, you convert the result to minutes:
hence, Richard saves 25.5 min (25 min and 30 s) when he drives with a speed of 80mph
Answer:
V₂ = - m₁ V₁ / m₂
Explanation:
According to law of conservation of momentum, "Total momentum of an isolated system remains constant. i.e
Pi = Pf
We consider ball and catapult an isolated system.
before launching ball momentum of the system is zero.
After launching ball momentum of ball is:
Pb= 0.1 * 500 = 50 kg m/s
Now according to law of conservation of momentum:
Pf = Pi
⇒ Pb + Pc = 0
Let Pb= m₁ V₁
& Pc = m₂ V₂
So
m₁ V₁ + m₂ V₂ = 0
⇒ V₂ = - m₁ V₁ / m₂
The negative sing shows that catapult velocity will have opposite direction to the ball velocity.
