GED Science Preparation Course：Physical science: energy, motion and matter

1. 第1题，共18题

   A ball rests on top of a shelf. What kind of energy does it have because of its position?

   • APotential energy
   • BNuclear energy
   • CKinetic energy
   • DSound energy
   显示答案

   答案: A. Potential energy

   A raised object stores gravitational potential energy. It gains kinetic energy only when it moves.

2. 第2题，共18题

   What energy changes happen in a battery-powered flashlight?

   • AElectrical → chemical → nuclear and heat
   • BLight → chemical → sound and motion
   • CHeat → light → chemical
   • DChemical → electrical → light and heat
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   答案: D. Chemical → electrical → light and heat

   The battery stores chemical energy, which becomes electrical energy, then light and some heat in the bulb.

3. 第3题，共18题

   A car engine uses fuel energy, but much of it becomes heat. What happens to the total amount of energy?

   • AIt increases because the car moves
   • BIt is destroyed inside the engine as fuel burns
   • CIt stays the same; it only changes form
   • DIt turns into mass
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   答案: C. It stays the same; it only changes form

   Energy cannot be created or destroyed. Some always changes into less useful heat.

4. 第4题，共18题

   A metal spoon in hot soup gets hot at the handle. How did the heat travel?

   • AConvection
   • BEvaporation
   • CConduction
   • DRadiation
   显示答案

   答案: C. Conduction

   Conduction is heat transfer by direct contact, through the metal from the hot end to the cool end.

5. 第5题，共18题

   How does heat from the Sun reach Earth through empty space?

   • ACondensation
   • BConduction
   • CConvection
   • DRadiation
   显示答案

   答案: D. Radiation

   Radiation travels as electromagnetic waves and needs no matter, so it can cross space.

6. 第6题，共18题

   You squeeze an instant cold pack and it gets cold. What kind of reaction is happening?

   • ANuclear
   • BCombustion
   • CExothermic
   • DEndothermic
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   答案: D. Endothermic

   An endothermic reaction absorbs heat from its surroundings, so it feels cold.

7. 第7题，共18题

   Which is a renewable energy source?

   • ACoal
   • BOil
   • CWind
   • DNatural gas
   显示答案

   答案: C. Wind

   Wind is replaced naturally. Coal, natural gas and oil are fossil fuels that run out.

8. 第8题，共18题

   Which type of electromagnetic wave has the most energy?

   • AVisible light
   • BInfrared
   • CRadio waves
   • DGamma rays
   显示答案

   答案: D. Gamma rays

   From low to high energy: radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays. Higher frequency means more energy.

9. 第9题，共18题

   A runner covers 400 m in 80 seconds. What is her average speed?

   • A0.2 m/s
   • B320 m/s
   • C32,000 m/s
   • D5 m/s
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   答案: D. 5 m/s

   Speed = distance ÷ time = 400 ÷ 80 = 5 m/s.

10. 第10题，共18题

    A car speeds up from 0 to 20 m/s in 4 seconds. What is its acceleration?

    • A80 m/s²
    • B0.2 m/s²
    • C5 m/s²
    • D16 m/s²
    显示答案

    答案: C. 5 m/s²

    Acceleration = change in speed ÷ time = (20 − 0) ÷ 4 = 5 m/s².

11. 第11题，共18题

    A 1,200 kg car moves at 15 m/s. What is its momentum?

    • A18,000 kg·m/s
    • B80 kg·m/s
    • C1,215 kg·m/s
    • D1,185 kg·m/s
    显示答案

    答案: A. 18,000 kg·m/s

    Momentum = mass × velocity = 1,200 × 15 = 18,000 kg·m/s.

12. 第12题，共18题

    What force is needed to give a 50 kg cart an acceleration of 2 m/s²?

    • A25 N
    • B48 N
    • C100 N
    • D52 N
    显示答案

    答案: C. 100 N

    Newton's second law: force = mass × acceleration = 50 × 2 = 100 N.

13. 第13题，共18题

    A rocket pushes hot gas down, and the rocket moves up. Which law explains this?

    • ANewton's first law
    • BNewton's third law
    • CThe law of superposition
    • DThe 10% rule
    显示答案

    答案: B. Newton's third law

    Newton's third law: every action has an equal and opposite reaction.

14. 第14题，共18题

    A worker lifts a box with a force of 200 N through a height of 3 m in 10 seconds. What is the worker's power?

    • A2,000 W
    • B600 W
    • C60 W
    • D6,000 W
    显示答案

    答案: C. 60 W

    Work = 200 × 3 = 600 J. Power = work ÷ time = 600 ÷ 10 = 60 W. 600 is the work, not the power.

15. 第15题，共18题

    A block has a mass of 60 g and a volume of 75 mL. Water's density is 1 g/mL. What is the block's density, and will it float?

    • A0.8 g/mL; it sinks
    • B0.8 g/mL; it floats
    • C1.25 g/mL; it floats
    • D1.25 g/mL; it sinks
    显示答案

    答案: B. 0.8 g/mL; it floats

    Density = 60 ÷ 75 = 0.8 g/mL. It is less dense than water, so it floats. 1.25 comes from dividing volume by mass.

16. 第16题，共18题

    In the balanced equation 2H₂ + O₂ → 2H₂O, how many hydrogen atoms are on the product side?

    • A6
    • B2
    • C3
    • D4
    显示答案

    答案: D. 4

    In 2H₂O, multiply the coefficient by the subscript: 2 × 2 = 4 hydrogen atoms, the same as the 4 in 2H₂.

17. 第17题，共18题

    In a sealed bag, 10 g of baking soda reacts with 50 g of vinegar. Gas forms, but nothing leaves the bag. What is the total mass after the reaction?

    • A60 g
    • BMore than 60 g, because gas formed
    • C40 g
    • D50 g
    显示答案

    答案: A. 60 g

    Mass is conserved in a chemical reaction. Nothing escaped, so the total stays 10 + 50 = 60 g.

18. 第18题，共18题

    An astronaut has a mass of 70 kg on Earth. What is her mass on the Moon?

    • AAbout 420 kg
    • BAbout 12 kg
    • C0 kg
    • D70 kg
    显示答案

    答案: D. 70 kg

    Mass is the same everywhere. Her weight (the pull of gravity) is less on the Moon, but her mass is not.

键盘：按1–4作答，按 Enter 进入下一题。

真实考试：145 on a 100–200 scale