Answer:
30 N
Explanation:
there are two forces act on the bar:
- weight of 1.5 kg mass, w = mg = 15 N
- weight of the bar, wb
for balance,
w * Lw = wb * Lwb
Lw = length of bar from the mass to the pivot
Lwb = lenght of bar from the center of the bar to the pivot
15 * 20 = wb * (50-20)
300 = wb * 30
wb = 300/30 = 30 N
We have that the block is moving horizontally. Hence, its potential energy due to gravity stays the same. The only change in its mechanical energy is the one due to the change of speed. This reduction of its kinetic energy, due to the conservation of energy, is equal to the work that friction does. We have that at A the kinetic energy is : K=1/2*m*u^2=10*10*10/2=500J. At B, we have that K=1/2*10*16=80J. Sine we have that the initial value is 500, the work from the friction force (opposite to the movement of the object) is 80-500=420J.
Answer:
it should be changes in velocity
Explanation:
I hope this helps!
Given constant acceleration, we can get the final position of an object in terms of both its initial velocity and its acceleration using one of the equations of motion.
The equation that we will use is:
Xf = Xi + Vi*t + (1/2)*a*t^2
where:
Xf is the final position of the object
Xi is the initial position of the object
Vi is the initial velocity of the object
t is the time
a is the constant given acceleration
Running on sand requires 1.6 times more energy spent than running on hard surface, so the force applied by our foot on sand is less.
