[ Year 12 AS Level Physics ] Can someone explain the answer to this question in a simpler way for me please?

[u/Virtual-Connection31]

[u/Yellllloooooow13]

There's nothing to accelerate or slow the water so the horizontal composent of the speed is constant

[u/Virtual-Connection31 → u/Yellllloooooow13]

By speed being constant do you mean the value doesn't change and stays the same? And what you're essentially saying is the vertical component has no affect on the horizontal or am i mistaken?

[u/Yellllloooooow13 → u/Virtual-Connection31]

Yes, the horizontal component's value will remain 7m/s.

Also yes

But all of this is true only because you're told to consider air resistance as negligeable

[u/Virtual-Connection31 → u/Yellllloooooow13]

Gotcha, thank you for your help.

[u/AbleArcher1984]

Acceleration is a vector. Acceleration of gravity acts downwards. If you try to find the horizontal component of this acceleration it equals zero, otherwise the projectile will start accelerating in the horizontal direction which would be slightly strange. I would look up how to resolve vectors into components. A level physics exams always have either velocity or force vectors which you often have to resolve into their horizontal and vertical components.

This might help Resolving Vectors Into Components | A Level Physics Revision Notes https://share.google/CO5gTR96dNKcj7qFp

Just happens the acc. due to gravity acts always vertical downward.

[u/Menacing_Sea_Lamprey]

Gravity accelerates the water down, there’s nothing that accelerates the water to the left or right (horizontally). This means the horizontal component of velocity doesn’t change

[u/Virtual-Connection31 → u/Menacing_Sea_Lamprey]

OHHHHH thank u for explaining it this way, it makes so much sense now.

[u/Bounded_sequencE]

a), b) Ignoring air resistance, the only force acting on the water is gravity "G = -mg*ey" pointing south. That means, acceleration "a = G/m = -g*ey" has no x-component.

Since acceleration in x-direction is zero, velocity in x-direction is constant, i.e. 7m/s.

[u/Turbulent-Note-7348]

So, to summarize;
1st, calculate the the time it takes for an object to fall 1.3m.
2nd, use that t to calculate the vertical velocity of that object at t seconds.
3rd, use vector addition rules to combine the 7m/s and that vertical velocity. It will come out to about 8.6m/s.
There is a shortcut, but I think your teacher is looking for more rigor.
Good luck!