Answer:
B. 4 m/s
Explanation:
v=d/t
Running for 300 m at 3 m/s takes 100 seconds and running at 300 m at 6 m/s takes 50 seconds. 100 s + 50 s = 150 s (total time). Total distance is 600 m, so 600 m/ 150 s = 4 m/s.
Answer:
The force of the car engine.
Explanation:
The work- energy theorem states that the work done on an object is equal to the change in its kinetic energy. Its expression is given by :

Also, W = F.d
Where
F is the force applied by the engine of car
d is the displacement
m is the mass of an object
u is the initial speed
v is the final speed
So, the force of the car engine increased the car’s kinetic energy. Hence, this is the required solution.
Answer:
c
Explanation:
If you double your speed, the energy dissipated in a crash is four times greater
Because impact increases with square of increase in speed.
Answer:
The velocity of the collar will be 3.076 ft/s
Explanation:
Given data
weight of the disk, Wa = 20lb
weight of rod BC, Wbc = 4lb
weight of collar, Wc = 1lb
Considering the equation of equilibrium
Vb = 1.5Wbc
Wa = 1.875 Wbc
to calculate the velocity of the collar using energy conservation equation
T1 + V1 = T2 + V2
=>
=>
=>
Wbc = 1.18rad/sec
i.e.

= 3.076 ft/ s