if the velocity of the car reduces from 70km/h to 50km/h then the speed of the car will be equal to the speed of the lorry...
thus the relative velocity will be 0
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
Answer:
9.8kW
Explanation:
Given data
Mass= 60kg
Hieght= 4m
Time= 4.2seconds
We know that the energy possessed is given as
PE=mgh
PE=60*9.81*4
PE= 2354.4 Joulse
Also, the expression for power is
Power=Energy*Time
Power= 2354.4*4.2
Power=9888.48 watt
Power= 9.8kW
The answer is : C ) air,water,and the tank glass.
-Hope this helps.