Download Science Math Exam Review Worksheet 1 Energy Problems: 1. What

Science Math Exam Review Worksheet 1
Energy Problems:
1. What is the kinetic energy of a jogger with a mass of 65.0 kg traveling at a speed of 2.5 m/s? (203.125 or 200 with bar
over the first zero J)
2. What is the mass of a baseball that has a kinetic energy of 105 J and is traveling at 10 m/s? (7.1kg, or 7 kg)
3. Find the gravitational potential energy of a light that has a mass of 13.0 kg and is 4.8 m above the ground. (611.52 or
610J)
4. A student lifts his 2.0 kg pet rock 2.8 m straight up. He then lets it drop to the ground. Use the Law
of Conservation of Energy to calculate how fast the rock will be moving (a) half way down and (b)
just before it hits the ground. Use TE1=TE2
a) 5.2 m/s
b) 7.4 m/s
5. A 65 kg girl is running with a speed of 2.5 m/s. How much kinetic energy does she have? She grabs
on to a rope that is hanging from the ceiling, and swings from the end of the rope. How high off the
ground will she swing? Use TE1=TE2 Ek = 203 J, Ep = 203 J therefore h = 0.32 m
6. A truck moving with a speed of 90 km/h 25 m/s loses it brakes but sees a “runaway” hill near
the highway. If the driver steers his vehicle into the runaway hill, how far up the hill (vertically)
will the vehicle travel before it comes to a stop? (Ignore friction.) If friction is taken into account,
will the vertical distance the vehicle moves be less or greater than the ‘ideal’ distance you just
solved for, neglecting friction? Explain. Use TE1 = TE2 If friction were to be taken into account,
we would expect that the height would be less since some energy would be lost (probably
as heat or sound).
(1 ohm) 7. A circuit contains two 1.5 volt batteries and a bulb with a resistance of 3 ohms. Calculate the
current. (
(120V) 8. What is the voltage of a circuit with 15 amps of current and toaster with 8 ohms of resistance?
9) Given this circuit:
If R1=15ohms, R2=20ohms and R3=5ohms, what are the currents at point 1, at point 3 and
between points 2 and 5. Each battery has a voltage of 12V (and there are two of them).
(I1=1.886A, I3=1.2A, I2-5=.686A or 2A, 1, A and 1 A)
10. What is the total power of the circuit? Electrical energy used if its on for 3 hours? (45watts
or 50 watts, .135 kwh or .1 kwh)