If you drop a 1.0 kg weight from a height of 1.0 m, how many joules of kinetic energy will it have when it reaches the ground?
Can I use the equation for work: W = F*s to find the kinetic energy?
Or would I have to find the velocity of the weight as it falls because I'm not sure how to do that.
To determine the kinetic energy (KE) of the weight when it reaches the ground, you can indeed use the equation for work (W) in conjunction with the formula for kinetic energy.
First, let's calculate the work done on the weight during its fall. The equation for work is W = F * s, where F is the force and s is the distance. In this case, the force acting on the weight is its weight, which can be calculated using the equation F = m * g, where m is the mass (1.0 kg) and g is the acceleration due to gravity (approximately 9.8 m/s^2).
Using these values, the force on the weight is F = 1.0 kg * 9.8 m/s^2 = 9.8 N.
Next, we need to determine the distance the weight falls (s), which is given as 1.0 m.
Now we can calculate the work done on the weight using W = F * s:
W = 9.8 N * 1.0 m = 9.8 J (Joules)
Since work done is equal to the change in kinetic energy, the kinetic energy of the weight when it reaches the ground is also 9.8 Joules.
To find the kinetic energy of the weight when it reaches the ground, you can use the equation KE = 1/2 * m * v^2, where KE represents the kinetic energy, m represents the mass, and v represents the velocity.
First, let's calculate the velocity of the weight as it falls. You can use the equation for free fall: v = sqrt(2 * g * h), where g is the acceleration due to gravity (approximately 9.8 m/s^2) and h is the height.
Substituting in the values, we get v = sqrt(2 * 9.8 * 1.0) = sqrt(19.6) ≈ 4.43 m/s.
Now that we have the velocity, we can calculate the kinetic energy using the formula KE = 1/2 * m * v^2. Given that the mass is 1.0 kg, we have KE = 1/2 * 1.0 * (4.43)^2 = 1/2 * 1.0 * 19.6 ≈ 9.8 joules.
So, the weight will have approximately 9.8 joules of kinetic energy when it reaches the ground.
You can do it either way.
The work done (by gravity) is
M*g*H = 9.8 Joules
That equals the final kinetic energy.
Vfinal = sqrt(2 g H)
(1/2)M*Vfinal^2 = M g H