Johnny stretches a spring 40 cm from its resting position. The spring’s constant of proportionality is 20 N/m. What is the sprin
1 answer:
The spring potential energy is 1.6 J
Explanation:
The elastic potential energy of a spring is given by the equation:
where
U is the potential energy
k is the spring constant
x is the compression/stretching of the spring
For the spring in this problem, we have:
x = 40 cm = 0.40 m is the stretching
k = 20 N/m is the spring constant
Substituting into the equation, we can find the spring potential energy:
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Answer:
v = 11.1m/s
Vx = 7.19m/s
Vy = 8.45m/s
V(sedan) = 30.4m/s
V(suv) = 25.9m/s
Explanation:
The force of gravity between two objects is given by:
where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is their separation
In this problem, the mass of the object is
, while the Earth's mass is 
. Their separation is 
, therefore the gravitational force exerted on the object is
where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is their separation
In this problem, the mass of the object is
Answer:
a) The average velocity is v = (60 km/h ; 0)
b) The average speed is 60 km/h
Explanation:
The velocity is a vector that has a magnitude and direction. The average speed is the distance traveled over time without taking into account the direction of the motion.
a)The average velocity is calculated as the displacement over time:
v = Δx/Δt
where
v = velocity
Δx = final position - initial position = traveled distance relative to the center of the reference system.
Δt = final time - initial time (initial time is usually = 0)
We know that the displacement is 84 km but we do not know the time. It can be calculated from the two parts of the trip.
In part 1:
v = 45 km/h = 42 km / t
t = 0.93 h
In part 2:
v = 90 km/h = 42 km / t
t = 42 km / 90 km/h
t = 0.47 h
The time of travel is 0.47 h + 0.93 h = 1.4 h
The average velocity will be:
v = 84 km / 1.4 h = 60 km/h
Expressed as a vector in a 2-dimension plane:
v = (60 km/h; 0)
b) The average speed is calculated as the distance traveled over time. Note that in this case, the distance is equal to the displacement since the direction of the motion is always in one direction. But if the direction of the second part of the trip would have been the opposite to the direction of the first part, the displacement would have been 0 (final position - initial position = 0, because final position = initial position), then, the average velocity would have been 0. In change, the average speed would have been the distance traveled (84 km, 42 km in one direction and 42 km in the other) over time.
Then:
average speed = 84 km / 1.4 h = 60 km/h
c) see attached figure.
