Yes, gravels can slow down the speed of a river by creating friction and obstacles which impede the flow of water. The rough surfaces of the gravel bed can decrease the velocity of the river as the water has to navigate around and through the individual particles.
These are some things that cause the speed of water to slow down. Broad flat channels slow a river down, a rough channel will also slow the water down. Basically, anything that increases the surface area of a body of water, against which water flows will slow it down, this is due to the increase of friction. In addition, water flows slowest at the margins of a river, if the river is winding, water will flow slower at the inside curves.
I think you mean slow down and speed up. slow down =slow, speed up=fast
slow down
In space, there is no air resistance to slow down spacecraft traveling at constant velocity. Additionally, spacecraft can use thrusters or gravitational assists to adjust their speed if needed. The laws of physics allow spacecraft to maintain their speed in the vacuum of space.
speed you up
Speed up
Slow Down to the Speed of Virginia - 2013 was released on: USA: February 2013
Nothing happens to the forces. The forces are what makes the thing speed up or slow down.
You dont put in anything to slow it down, you simply reduce the temperature thus causing the reaction to slow down
Slow Down Speed Up - 1967 TV was released on: USA: 1 June 1967
Every car slows down for speed bumps... that's what speed bumps are for.