Kinetic Energy and the Work/Energy Theorem:
1.) How much kinetic energy does a 700-gram baseball have that is travelling at 20 m/s? What would be the kinetic energy if you doubled the mass? What would be the kinetic energy if you doubled the velocity?
3.How much work must gravity do on a 2-kg falling object in order to take it from rest to 20 m/s?
5.) A 5-kg box is sliding across a desk that has a coefficient of friction of 0.4. If the box is initially moving at 15 m/s, how far will the box slide before coming to rest. How can can you use the work or Kinetic Energy Theorem to solve this??
KE = 1/2 mv^2
W = KE
once again KE = Fd
The F is Friction = mu Fn = mu mg in this case.
A man of mass 90kg is moving at a constant velocity he has a kinetic energy of 2205kg calculate his velocity
A MASS OF 90KG IS MOVING AT A CONSTANT VELOCITY HE HAS KINETIC ENERGY OF 2205 CALCULATE THE VELOCITY
V=2205×90=198450
Is it 5000
Joules
1. To calculate the kinetic energy of an object, you need to use the formula:
Kinetic Energy = (1/2) * mass * velocity^2
For the given baseball with a mass of 700 grams (or 0.7 kg) and a velocity of 20 m/s, the calculation would be:
Kinetic Energy = (1/2) * 0.7 kg * (20 m/s)^2 = 140 Joules
If you double the mass to 1.4 kg while keeping the velocity constant at 20 m/s, the new kinetic energy would be:
Kinetic Energy_2 = (1/2) * 1.4 kg * (20 m/s)^2 = 280 Joules
If you double the velocity to 40 m/s while keeping the mass constant at 0.7 kg, the new kinetic energy would be:
Kinetic Energy_3 = (1/2) * 0.7 kg * (40 m/s)^2 = 560 Joules
3. To determine the work that gravity does on a falling object, you can use the work-energy theorem. The work done by gravity is equal to the change in kinetic energy of the object.
In this case, the object starts from rest, so its initial kinetic energy is zero. The final velocity is 20 m/s, and the mass is 2 kg. Therefore, the work done by gravity would be:
Work = Change in Kinetic Energy = Final Kinetic Energy - Initial Kinetic Energy
= (1/2) * 2 kg * (20 m/s)^2 - 0
= 400 Joules
So, gravity must do 400 Joules of work on the 2-kg falling object to take it from rest to 20 m/s.
5. To determine how far the box will slide before coming to rest, you can use the work-energy theorem or the concept of mechanical work.
The work done by the friction force can be calculated as:
Work = Force of friction * distance
The force of friction is given by the equation:
Force of friction = coefficient of friction * normal force
In this case, the normal force would be equal to the weight of the box, which is the mass multiplied by the acceleration due to gravity (9.8 m/s^2).
The work done by friction also equals the change in kinetic energy of the box. Initially, the box has a kinetic energy of (1/2) * 5 kg * (15 m/s)^2, and when it comes to rest, the kinetic energy becomes zero.
So, you can set up the equation:
(1/2) * 5 kg * (15 m/s)^2 = coefficient of friction * 5 kg * 9.8 m/s^2 * distance
Simplifying the equation and solving for distance would give you the value of how far the box will slide before coming to rest.