Worksheet on kinetic and gravitational potential energy with calculations.

Explanation:
Let’s go through each problem one by one. First, remember:

- Kinetic energy (KE) is the energy of motion → use formula:
KE = ½ m v²
where *m* = mass in kg, *v* = speed in m/s.

- Gravitational potential energy (GPE) is the energy due to height → use formula:
GPE = m g h, but since weight *W = m g*, and weight is given in newtons (N), we can simplify to:
GPE = weight × height = W × h
(since *W = mg*, so *mgh = Wh*).
So if weight is given (in N) and height (in m), just multiply them.

Now solve each:

1. Volleyball: mass = 2.1 kg, speed = 30 m/s → moving → kinetic energy
KE = ½ × 2.1 × (30)² = 0.5 × 2.1 × 900 = 1.05 × 900 = 945 J

2. Baby carriage at top of hill: height = 21 m, weight = 12 N → not moving, elevated → gravitational potential energy
GPE = weight × height = 12 N × 21 m = 252 J

3. Car moving: velocity = 40 m/s, mass = 1120 kg → motion → kinetic energy
KE = ½ × 1120 × (40)² = 560 × 1600 = 896,000 J

4. Cinder block on platform: height = 20 m, weight = 79 N → elevated, not moving → gravitational potential energy
GPE = 79 × 20 = 1,580 J

5. Bell on tower: height = 45 m, weight = 190 N → elevated → gravitational potential energy
GPE = 190 × 45 = let’s compute: 200×45 = 9,000; subtract 10×45 = 450 → 9,000 − 450 = 8,550 J

6. Roller coaster at top of hill: height = 72 m, weight = 966 N → elevated → gravitational potential energy
GPE = 966 × 72
Break it down:
900 × 72 = 64,800
66 × 72 = (60×72) + (6×72) = 4,320 + 432 = 4,752
Total = 64,800 + 4,752 = 69,552 J

7. 25 kg object moving at 5 m/s → motion → kinetic energy
KE = ½ × 25 × (5)² = 0.5 × 25 × 25 = 12.5 × 25 = 312.5 J

Let me double-check all calculations:

1. 0.5 × 2.1 = 1.05; 1.05 × 900 = 945 ✔
2. 12 × 21 = 252 ✔
3. 0.5 × 1120 = 560; 560 × 1600 = 896,000 ✔
4. 79 × 20 = 1,580 ✔
5. 190 × 45: 19×45 = 855 → ×10 = 8,550 ✔
6. 966 × 72:
966 × 70 = 67,620
966 × 2 = 1,932
Sum = 67,620 + 1,932 = 69,552 ✔
7. 0.5 × 25 = 12.5; 12.5 × 25 = 312.5 ✔

All correct.

Final Answer:
1. kinetic, 945 J
2. gravitational potential, 252 J
3. kinetic, 896000 J
4. gravitational potential, 1580 J
5. gravitational potential, 8550 J
6. gravitational potential, 69552 J
7. kinetic, 312.5 J