2.0 meters The skateboarder has 2 forces acting upon him to slow him down. The forces are friction, and climbing against the gravitational acceleration. So let's calculate the magnitude of these forces to see how fast he's decelerated. The coefficient of kinetic friction is a multiplier to use against the normal force of the object. We can calculate the normal force by multiplying the mass of the object by the local gravitational acceleration and the cosine of the angle. So Df = 60 kg * 9.8 m/s^2 * cos(20°) * 0.30 Df = 60 kg * 9.8 m/s^2 * 0.939692621 * 0.30 Df = 60 kg * 9.8 m/s^2 * 0.939692621 * 0.30 Df = 165.7617783 kg*m/s^2 Df = 165.7617783 N
The second amount of force is that caused by gravitational acceleration while climbing. That is determine by the amount of height gained for every meter along the slope. We can calculate that using the sine of the angle. So
Dg = 60 kg * 9.8 m/s^2 * sin(20°)
Dg = 60 kg * 9.8 m/s^2 * 0.342020143
Dg = 201.1078443 kg*m/s^2
Dg = 201.1078443 N
So the amount of force decelerating the skateboarder is:
F = Df + Dg
F = 165.7617783 N + 201.1078443 N
F = 366.8696226 N
Now let's determine how much kinetic energy needs to be dissipated. The equation is
E = 0.5 MV^2
So we'll substitute the known values and calculate
E = 0.5 MV^2
E = 0.5* 60 kg * (5 m/s)^2
E = 0.5* 60 kg * 25 m^2/s^2
E = 750 kg*m^2/s^2
E = 750 J
Now let's divide the energy by the force.
750 kg*m^2/s^2 / 366.8696226 kg*m/s^2 = 2.04432298 m
Rounding to 2 significant figures gives a distance of 2.0 meters.
Using the average velocity formula which is total distance divided by total time. If the distance is given in km convert to m then divide by 1000 to get m and if time is given in minutes then divide by 60 to get seconds. And after converting, divide to get your final answer in m/s. Hope that helped!
The two factors that increase the size of a population are natality, which is the number of individuals that are added to the population over a period of time due to reproduction, and immigration, which is the migration of an individual into a place.
Answer:
Barret True, the speed decreases with increasing time
Explanation:
The equation they give us to describe the movement is of the form
y = yo + v₀ t + ½ a t²
The given equation is
y = -4 - 9 t + 2 t²
We can match term to term and find the constants
y₀ = -4 m
v₀ = -9 m / s
a = 2 m / s²
With this data we can build the equation of speed and time
v = v₀ + a t
v = - 9 + 2 t
With this expression we see that as time increases the speed decreases since the speed and acceleration have direction is opposite
Now we can analyze the students' observations
Amadeo False, we see that the behavior is the opposite
Barret True, the speed decreases with increasing time
Chinue False With the equation we have all the data to build the speed equation as a function of time
