der Schwung
momentum
A fast, often arcing movement that arises from an impulse and carries a certain force or energy with it.
Er öffnete die Tür mit Schwung und trat ein.
He opened the door with momentum and stepped inside.

momentum / energy
Loading your saved state.
momentum
A fast, often arcing movement that arises from an impulse and carries a certain force or energy with it.
Er öffnete die Tür mit Schwung und trat ein.
He opened the door with momentum and stepped inside.

The noun 'der Schwung' (momentum/energy) is closely related to the verb 'schwingen' (to swing). A swinging movement generates momentum, which helps you understand the basic meaning of energy and movement.
Die Turnerin holte auf der Schaukel Schwung für ihren Absprung.
The gymnast built up momentum on the swing for her jump.
To describe a movement, the phrase 'Schwung holen' (to build up momentum) is often used for the preparation, and 'mit Schwung' (with momentum) for the execution.
Der Golfer holt mit dem Schläger Schwung und schlägt den Ball.
The golfer builds up momentum with the club and hits the ball.
When talking about motivation, people often speak of having 'neuen Schwung' (new energy) or being 'voller Schwung' (full of energy). You can also 'mitnehmen' (carry forward) or 'verlieren' (lose) the momentum.
Nach dem erfolgreichen Projektstart wollen wir den Schwung mitnehmen.
After the successful project launch, we want to carry the momentum forward.
The phrase 'in Schwung kommen' (to get going) means that something slowly starts to function or become lively. With 'etwas in Schwung bringen' (to get something going), you can actively start this process.
Am Montagmorgen brauche ich immer einen Kaffee, um in Schwung zu kommen.
On Monday mornings, I always need a coffee to get going.
The meaning 'eine große Menge' (a large amount) is colloquial. It is often used in the form 'ein ganzer Schwung' (a whole batch) to talk about a group of things or people that arrive all at once.
Der Postbote hat heute einen ganzen Schwung Pakete für die Nachbarn gebracht.
The mail carrier brought a whole batch of packages for the neighbors today.
In this meaning, 'Schwung' (sweep/flourish) describes an elegant, curvy line. People often say that handwriting or a drawing 'einen schönen Schwung hat' (has a beautiful flourish).
Die Kalligrafin zog die Buchstaben mit elegantem Schwung.
The calligrapher formed the letters with an elegant flourish.
amount / crowd
'die Menge' and 'der Schwung' can both mean a larger number of things or people. 'die Menge' is neutral and general. You use it when you simply want to say that there is a lot of something. In this meaning, 'der Schwung' is more colloquial and often means a group or number that comes, is brought, or is dealt with all at once. Learners may confuse the words because both can express 'a lot'. As a practical rule: for precise or neutral statements, 'Menge' is better; for casual everyday language with the idea of 'all at once', 'Schwung' is more likely to fit.

Am Nachmittag kam ein ganzer Schwung neuer Kunden in den Laden.
In the afternoon, a whole batch of new customers came into the store.
Sarah wundert sich über die große Menge an E-Mails nach dem Urlaub.
Sarah is surprised by the large number of emails after her vacation.