Yr 10 Physics Questions - 2024 (Exam Revision) PDF

## Physical Sciences - Trial Test Solutions 1. Copy and complete the statements below to compile a summary of this chapter. The missing words can be found in the list below. a. Speed is a measure of the **rate** at which an object moves over a distance. b. **Average speed** can be calculat...

## Physical Sciences - Trial Test Solutions 1. Copy and complete the statements below to compile a summary of this chapter. The missing words can be found in the list below. a. Speed is a measure of the **rate** at which an object moves over a distance. b. **Average speed** can be calculated by dividing the distance travelled by the time taken. c. **Velocity** is a measure of the rate of change in position. In order to describe the velocity fully, the direction of the change in position must be stated. d. The **instantaneous speed** of an object is its speed at a particular instant of time. e. The **acceleration** of an object moving in a straight line is a measure of the rate at which it changes speed. f. The **average acceleration** of an object can be calculated by dividing the change in its speed by the time taken for the change. g. An object will remain at rest, or will not change its speed or direction unless it is acted upon by an outside, **unbalanced force**. h. The acceleration of an object depends on the mass of the object and the **total force** acting on it. i. When an object applies a force to a second object, the second object applies an **equal and opposite force** to the first object. j. All stored energy is called **potential energy**. k. The Law of Conservation of Energy states that energy is never created or **destroyed**. | Average | Distance | Instantaneous | Total | Weight | |---|---|---|---|---| | Energy | Destroyed | Velocity | Work | Force | | Direction | Equal | Potential | Acceleration | Opposite | | Unbalanced | Dividing | Change | Rate | Gravitational | 2. Explain why the following statement is false. "A car travelling along a straight road has no forces acting on it." Applied force (thrust), gravity, friction, **upward force from road (normal)**. 3. The table below provides information about four laps completed by one of the drivers in an Australian Formula One Grand Prix. The distance covered during one complete circuit of the course is 5.3 km. a. Make a copy of the table and fill in the empty cells. | Lap No | Time (s) | Average speed (m/s) | Average speed (km/h) | |---|---|---|---| | 5 | 90 | 58.89 | 212 | | 15 | 88.3 | 60 | 216 | | 25 | 110 | 48.18 | 173.5 | | 35 | 92 | 57.6 | 207.4 | ### 4. Complete these statements about Newton's Laws of Motion in your workbook. a. An object remains at rest, or will not change its speed or direction unless **acted upon by an unbalanced force**. b. When an unbalanced force acts on an object, the mass of an object affects **acceleration**. c. For every action, there is **an equal and opposite reaction**. 5. Explain in terms of Newton's First Law of Motion why it is dangerous to have loose objects inside a moving car. An object will not change its motion unless acted upon by an unbalanced force. Braking/change direction may cause objects to fly around. 6. Newton's Second Law of Motion can be expressed as the formula F = ma. What quantities do each of the symbols in the formula represent? F= force (N), M=mass (kg), a=acceleration (m/s²). 7. Use Newton's Second Law to calculate answers for the following. a. A 1400 kg car accelerates at 3 m/s². What size force is needed to cause this acceleration? 1400 x 3 = 4200 N b. A force of 160 N causes an object to accelerate at 2 m/s². What is the object's mass? 160/2 = 80 kg. c. A force of 210 N acts on a mass of 70 kg. What is the acceleration? 210/70 = 3 m/s² 8. Classify the following as a type of potential energy or kinetic energy (use the letters K or P) a. A bicyclist pedalling up a hill **K** b. An archer with his bow drawn **P** c. A volleyball player spiking a ball **K** d. A baseball thrown to second base **K** e. The chemical bonds in sugar **P** f. The wind blowing through your hair **K** g. Walking down the street **K** h. Sitting in the top of a tree **P** i. A bowling ball rolling down the alley **K** k. A bowling ball sitting on the rack **P** ### Solve the following word problems using the kinetic and potential energy formulas Formulas: KE = ½mv² or PE = m.g.h v = velocity or speed m = mass in kg g = 9.8 m/s/s h = height in meters 10. A baby carriage is sitting at the top of a hill that is 21 m high. The carriage with the baby has **potential energy**. Calculate it. 1.5 x 9.8 x 21 = 308.7 J 11. A car is traveling with a velocity of 40 m/s and has a mass of 1120 kg. The car has **kinetic energy**. Calculate it. ½ (1120) x 40² = 896000 J 12. A cinder block is sitting on a platform 20 m high. It weighs 7.9 kg. The block has **potential energy**. Calculate it. 7.9 x 20 x 9.8 = 1548.4 J 13. A roller coaster is at the top of a 72 m hill and weighs 134 kg. The coaster (at this moment) has **potential energy**. Calculate it. 134 x 72 x 9.8 = 94550.4 J 14. Determine the kinetic energy of a 1000-kg roller coaster car that is moving with a speed of 20.0 m/s. KE = ½mv² = ½ 1000 (20)² = 200 000 J ### 15. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy? ½ 1000 (40)² = 800 000 J 16. The potential energy of a 40-kg cannon ball is 14000 J. How high was the cannon ball to have this much potential energy? 14000 = 40 x 9.8 x h h = 35.7 m 17. Law of Conservation of Energy Energy can be neither **created** or **destroyed** by ordinary means. Energy can be **converted** from one form to another. The total amount of energy is the **same** before and after any energy transformation. 18. Draw a free body diagram of the following scenarios: (a) An egg is free-falling from a nest in a tree. Neglect air resistance. Diagram the forces acting on the egg as it is falling. (b) A rightward force is applied to a book in order to move it across a desk with a rightward acceleration. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book. a.) | arrow pointing downward | arrow pointing upward | |---|---| | F(gravity) | | b.) | arrow pointing downward | arrow pointing upward | arrow pointing leftward | arrow pointing rightward | |---|---|---|---| | F(gravity) | F(normal) | F(friction) | F(applied) |