The "speed only" equivalent of vector is scalar
Answer:

Explanation:
We'll use the momentum equation:

where:
p = momentum
m = mass
v = velocity
Since we're doing the magnitude of momentum of the system, we'll add the mass of the cyclist and the mountain bike together:

Given that, we can now substitute our given values into the momentum equation:

Our final answer is:

Answer:
Yes.
Explanation:
A kilometer is less than a mile, therefore if a horse can finish one mile in less than 2 minutes then it can certainly do a kilometer in less than two minutes.
Answer:
5.5 x 10^5 N/C
Explanation:
t = 0.001 s
Δp = - 8.8 x 10^-17 kg m /s
Force is equal to the rate of change of momentum.
F = Δp / Δt
F = (8.8 x 10^-17) / 0.001 = 8.8 x 10^-14 N
q = 1.6 x 10^-19 C
Electric field, E = F / q = (8.8 x 10^-14) / (1.6 x 10^-19)
E = 5.5 x 10^5 N/C
We need more evidence to be provided