Consider the free body diagram. If the sum of the tension forces is equal to the force of gravity, which description BEST appli
es?
A) A book is at rest on a tabletop.
B) A physics student rests a backpack upon one shoulder.
C) A girl hangs by both hands, motionless, from a trapeze.
D) A girl falls slowly to Earth while strapped to a parachute.
A) A book is at rest on a tabletop.
B) A physics student rests a backpack upon one shoulder.
C) A girl hangs by both hands, motionless, from a trapeze.
D) A girl falls slowly to Earth while strapped to a parachute.
2 answers:
You might be interested in
Answers:
a) -2.54 m/s
b) -2351.25 J
Explanation:
This problem can be solved by the <u>Conservation of Momentum principle</u>, which establishes that the initial momentum must be equal to the final momentum
:
(1)
Where:
(2)
(3)
is the mass of the first football player
is the velocity of the first football player (to the south)
is the mass of the second football player
is the velocity of the second football player (to the north)
is the final velocity of both football players
With this in mind, let's begin with the answers:
a) Velocity of the players just after the tackle
Substituting (2) and (3) in (1):
(4)
Isolating :
(5)
(6)
(7) The negative sign indicates the direction of the final velocity, to the south
b) Decrease in kinetic energy of the 110kg player
The change in Kinetic energy is defined as:
(8)
Simplifying:
(9)
(10)
Finally:
(10) Where the minus sign indicates the player's kinetic energy has decreased due to the perfectly inelastic collision
