A 25-kg child sits at the top of a
4-meter slide. After sliding down, the child is traveling at 5 m/s. How much PE does he start with? How much KE does he end with? How much energy is lost to friction?
if you push a box across the floor with a force of 30 N you push it 15 meters in 8 seconds how much work will you do how much power did you use?
M*g = 25 * 9.8 = 245 N. = Wt. of child.
At bottom of slide:
a. PE = Mg*h = 245*4 = 980 J.
b. KE = 0.5M*V^2 = 0.5*25*5^2 = 312.5 J.
c. PE-KE = Energy lost to friction.
To calculate the potential energy (PE) at the top of the slide, we need to use the formula:
PE = mgh
Where m is the mass (25 kg), g is the acceleration due to gravity (9.8 m/s^2), and h is the height of the slide (4 m).
PE = 25 kg * 9.8 m/s^2 * 4 m
PE = 980 J
So the child starts with 980 Joules of potential energy.
To calculate the kinetic energy (KE) at the bottom of the slide, we use the formula:
KE = (1/2)mv^2
Where m is the mass (25 kg), and v is the velocity (5 m/s).
KE = (1/2) * 25 kg * (5 m/s)^2
KE = 1/2 * 25 kg * 25 m^2/s^2
KE = 625 J
So the child ends with 625 Joules of kinetic energy.
The energy lost to friction can be calculated by subtracting the final kinetic energy from the initial potential energy:
Energy lost to friction = PE - KE
Energy lost to friction = 980 J - 625 J
Energy lost to friction = 355 J
Therefore, 355 Joules of energy were lost to friction.
Now let's move on to the second question:
To calculate work, we use the formula:
Work = force * distance
Where force is the applied force (30 N), and distance is the distance moved (15 m).
Work = 30 N * 15 m
Work = 450 J
So you will do 450 Joules of work.
To calculate power, we use the formula:
Power = work / time
Where work is the amount of work done (450 J), and time is the time taken (8 seconds).
Power = 450 J / 8 s
Power = 56.25 W
So you used 56.25 Watts of power.