Physics

Question

A 2-kg bowling ball sits on top of a building that is 40 meters tall. Circle one: KE / GPE / both Show your work for finding the values of each type of energy the object has:

2. A 2-kg bowling ball rolls at a speed of 5 m/s on the roof of the building that is 40 tall. Circle one: KE / GPE / both Show your work for finding the values of each type of energy the object has:

3. A 2-kg bowling ball rolls at a speed of 10 m/s on the ground. Circle one: KE / GPE / both Show your work for finding the values of each type of energy the object has:

1. A 1,000-kg car has 50,000 joules of kinetic energy. What is its speed?

2. A 200-kg boulder has 39,200 joules of gravitational potential energy. What height is it at?

3. A 1-kg model airplane has 12.5 joules of kinetic energy and 98 joules of gravitational potential energy. What is its speed? What is its height?

1 Answer

  • 1. A 2-kg bowling ball sits on top of a building that is 40 meters tall. Circle one: KE / GPE / both Show your work for finding the values of each type of energy the object has:

    KE = 0 (because velocity is 0)

    PE = mgh = 2kg*9.8m/s^2*40m= 784 joule

    2. A 2-kg bowling ball rolls at a speed of 5 m/s on the roof of the building that is 40 tall. Circle one: KE / GPE / both Show your work for finding the values of each type of energy the object has:

    Both
    KE = [1/2]m*v^2 = [1/2](2kg)(5m/s)^2 =  25 joul
    PE = mgh = 40 joule

    3. A 2-kg bowling ball rolls at a speed of 10 m/s on the ground. Circle one: KE / GPE / both Show your work for finding the values of each type of energy the object has:

    KE = [1/2]m(v^2) = [1/2]2kg*(10m/s)^2 = 100 joule

    GPE = mgh = 0

    1. A 1,000-kg car has 50,000 joules of kinetic energy. What is its speed?

    KE = [1/2]m(v^2) => v = √[2KE/m] = √[2*50,000joules/1000kg] = 10m/s

    2. A 200-kg boulder has 39,200 joules of gravitational potential energy. What height is it at?

    GPE = mgh => h = GPE / (mg) = 39,200 joules / (200kg * 9.8m/s^2) = 20m

    3. A 1-kg model airplane has 12.5 joules of kinetic energy and 98 joules of gravitational potential energy. What is its speed? What is its height?

    KE = [1/2]m(v^2) => v = √ [ 2KE/m] = √[2*12.5 j / 1kg] = 7.9 m/s

    GPE = mgh => h = GPE/(mg) = 98/(1kg*9.8m/s^2) = 10 m
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