Answer: vl = 2.75 m/s vt = 1.5 m/s
Explanation:
If we assume that no external forces act during the collision, total momentum must be conserved.
If both cars are identical and also the drivers have the same mass, we can write the following:
m (vi1 + vi2) = m (vf1 + vf2) (1)
The sum of the initial speeds must be equal to the sum of the final ones.
If we are told that kinetic energy must be conserved also, simplifying, we can write:
vi1² + vi2² = vf1² + vf2² (2)
The only condition that satisfies (1) and (2) simultaneously is the one in which both masses exchange speeds, so we can write:
vf1 = vi2 and vf2 = vi1
If we call v1 to the speed of the leading car, and v2 to the trailing one, we can finally put the following:
vf1 = 2.75 m/s vf2 = 1.5 m/s
The density is 4.76 gcm^-3
and if mass is in kg then density is equal to 4.76*10^-3
Answer:
2 s, -20 m/s
Explanation:
Given:
y₀ = 20 m
y = 0 m
v₀ = 0 m/s
a = -9.8 m/s²
Find: t and v
y = y₀ + v₀ t + ½ at²
0 = 20 + 0 + ½ (-9.8) t²
0 = 20 − 4.9 t²
t ≈ 2 s
v² = v₀² + 2a(y − y₀)
v² = 0 + 2(-9.8)(0 − 20)
v ≈ ±20 m/s
Since the rock is falling, v = -20 m/s.
D is the answer the force excerted on the ball is greater than gravity
Answer:
The radius r of the metal sphere.
Explanation:
From Gauss's law we know that for a spherical charge distribution with charge 
, the electrical field at distance 
from the center of the sphere is given by
What is important to notice here is that the radius of the sphere does not matter because any test charge sitting at distance feels the force as if all the charge were sitting at the center of the sphere.
This situation is analogous to the gravitational field. When calculating gravitational force due to a body like the sun or the earth, we take not of only the mass of the sun and the distance from it's center; the sun's radius does not matter because we assume all of its mass to be concentrated at the center.
