Answer: Kinetic frictional force = 23.76N
Explanation: Please see the attachments below
Answer:
Nitrogen and oxygen are by far the most common; dry air is composed of about 78% nitrogen (N2) and about 21% oxygen (O2). Argon, carbon dioxide (CO2), and many other gases are also present in much lower amounts; each makes up less than 1% of the atmosphere's mixture of gases.
Let us examine the given situations one at a time.
Case a. A 200-pound barbell is held over your head.
The barbell is in static equilibrium because it is not moving.
Answer: STATIC EQUILIBRIUM
Case b. A girder is being lifted at a constant speed by a crane.
The girder is moving, but not accelerating. It is in dynamic equilibrium.
Answer: DYNAMIC EQUILIBRIUM
Case c: A jet plane has reached its cruising speed at an altitude.
The plane is moving at cruising speed, but not accelerating. It is in dynamic equilibrium.
Answer: DYNAMIC EQUILIBRIUM
Case d: A box in the back of a truck doesn't slide as the truck stops.
The box does not slide because the frictional force between the box and the floor of the truck balances out the inertial force. The box is in static equilibrium.
Answer: STATIC EQUILIBRIUM
Answer:
<u>velocity of swimmer relative to ground = 3 i -5 j</u>
Explanation:
- To cross a river the swimmer swims relative to river in perpendicular direction.
Velocity of river = -5 j (south)
Velocity of swimmer relative to river = 3 i(north)
So
<h2>
Velocity of swimmer relative to ground = Velocity of swimmer relative to river + Velocity of river</h2>
Velocity of swimmer relative to ground = 3 i -5 j
So magnitude of total velocity is 
=
= 
