Answer:
0.001 s
Explanation:
The force applied on an object is equal to the rate of change of momentum of the object:
where
F is the force applied
is the change in momentum
is the time interval
The change in momentum can be written as
where
m is the mass
v is the final velocity
u is the initial velocity
So the original equation can be written as
In this problem:
m = 5 kg is the mass of the fist
u = 9 m/s is the initial velocity
v = 0 is the final velocity
F = -45,000 N is the force applied (negative because its direction is opposite to the motion)
Therefore, we can re-arrange the equation to solve for the time:
Answer:
3.44 W/m²
1.134 J
Explanation:
E₀ = Intensity of electric field = 50.9 V/m
I = Intensity of electromagnetic wave
Intensity of electromagnetic wave is given as
I = (0.5) ε₀ E₀² c
I = (0.5) (8.85 x 10⁻¹²) (50.9)² (3 x 10⁸)
I = 3.44 W/m²
A = Area = 0.0277 m²
t = time interval = 11.9 s
Amount of energy is given as
U = I A t
U = (3.44) (0.0277) (11.9)
U = 1.134 J
It will depend on the frictional force involved in the two. I think it will take more force in sled.
Answer:
Explanation:
Work done by the spring is negative .
Work done by force F creating displacement d is given by the following expression .
Work = F x d
Both force and displacement are vector quantity .
When direction of force and direction of displacement is same , work is positive . When direction of force and direction of displacement is opposite , work is negative .
When spring is compressed , it exerts a restoring or opposing force in a direction opposite to the direction of displacement of box . Hence here force is opposite to displacement . Restoring force acts opposite to displacement . Hence work done by spring on box is negative .
