Solving Energy problems

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving?

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving?

Step 1 – Read the problem look for what is given.

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving?

Step 1 – Read the problem look for what is given.

Mass (m)= 0.1 kg

Kinetic Energy (ke) = 20 J

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving?

Step 2 – Read the problem look for key words.

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving?

Step 2 – Read the problem look for key words.1st key words(kinetic energy)

Use the kinetic energy formula ke = ½ m * v2

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving?

Step 2 – Read the problem look for key words.1st key words(kinetic energy)

Use the kinetic energy formula ke = ½ m * v2

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving?

Step 2 – Read the problem look for key words.1st key words(kinetic energy)

Use the kinetic energy formula ke = ½ m * v2

2nd key words (How fast)What you are looking for is the velocity v

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving? Ke = ½ m * v2

As you are looking for v you must first rearrange the equation to get everything on the other side of the = sign from v.To do this you must divide both sides of the

equation by ½ m.

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving? ke = ½ m * v2

ke = ½ m * v2

½ m ½ mThe ½ m’s on the right side of the equations cancel and

you end up with

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving? ke = ½ m * v2

ke = v2

½ mNow take the square root of both sides

(ke/ ½ m)½ = v

Solving Energy problems

A 0.1-kg baseball has 20 joules of kinetic energy as it passes over the plate. How fast is it moving? (ke/ ½ m)½ = v

Now fill in the values from the problem and solve(20 J/ ½ 0.1kg )½ = v (40 J/ 0.1kg )½ = v (400m2/s2)½ = v 20 m/s = v