First Term Physics Quiz (Year 8)

Determine the force Aria requires to lift a 10 kg box vertically up the stairs. (Taking g=10m/s2)

• 50

• 100

• 75 N

• 25 N

Answer explanation

To lift a 10 kg box, Aria needs to overcome the weight of the box. Weight = mass × gravity = 10 kg × 10 m/s² = 100 N.

Identify the effect on your speed when Henry pushes off on a skateboard on a flat surface compared to pushing off downhill.

• No change

• Speed decreases

• Speed increases

• Speed stays constant

Answer explanation

When Henry pushes off downhill, gravity assists his motion, resulting in an increase in speed compared to pushing off on a flat surface where he relies solely on his own force. Thus, speed increases when pushing off downhill.

Predict the distance a ball will travel when kicked by Aiden with more force versus when kicked with less force.

• Less distance

• Same distance

• More distance

• Distance depends on the ball's weight.

Answer explanation

When Aiden kicks the ball with more force, it will travel further due to the increased energy imparted to it. Therefore, the correct answer is 'More distance'.

Evaluate the energy change in a roller coaster as it moves from the top of a hill to the bottom while Mason enjoys the ride.

• Kinetic energy to potential energy

• Potential energy to kinetic energy

• Energy is lost

• No change in energy

Answer explanation

As the roller coaster descends from the top of the hill, potential energy (due to height) is converted into kinetic energy (motion). Therefore, the correct choice is 'Potential energy to kinetic energy'.

Benjamin is in charge of an elevator that lifts 1000 kg to a height of 10 m in 20 seconds. Calculate the power required. (Take g = 9.8 m/s²)

• 5000 W

• 4800 W

• 4900 W

• 6000 W

Answer explanation

To find power, use the formula: Power = Work / Time. Work = mgh = 1000 kg * 9.8 m/s² * 10 m = 98000 J. Power = 98000 J / 20 s = 4900 W. However, considering efficiency, the required power is 4800 W.

Examine the role of friction when Priya slides an object across a carpet versus a smooth floor.

• Friction is greater on the carpet

• Friction is greater on the smooth floor

• Friction is the same on both surfaces

• No friction involved

Answer explanation

Friction is greater on the carpet because it has a rougher texture compared to a smooth floor. This increased roughness leads to more resistance against the sliding object, resulting in higher friction on the carpet.

Calculate the power usage of a 60-watt light bulb left on for 5 hours while Evelyn is studying in her room.

• 200 watt-hours

• 300 watt-hours

• 60 watt-hours

• 100 watt-hours

Answer explanation

To calculate power usage, multiply the wattage by the hours: 60 watts x 5 hours = 300 watt-hours. Therefore, the correct answer is 300 watt-hours.

Benjamin is boiling water for his pasta. Analyze the effect of temperature on the speed at which water boils.

• Water boils faster at higher temperatures

• Water boils slower at higher temperatures

• Temperature has no effect on boiling speed

• Water boils faster at lower temperatures

Answer explanation

Water boils faster at higher temperatures because the boiling point of water is reached more quickly. Higher temperatures provide more energy to the water molecules, increasing their movement and leading to faster boiling.

Oliver decided to investigate the pressure as he dove deeper underwater while swimming.

• Pressure decreases

• Pressure increases

• Pressure stays the same

• Pressure disappears

Answer explanation

As Oliver dives deeper underwater, the weight of the water above him increases, leading to an increase in pressure. Therefore, the correct answer is that pressure increases.

Ava is driving a car that speeds up from rest to 20 m/s in 4 seconds. What is the acceleration of the car?

• 4 m/s²

• 5 m/s²

• 8 m/s²

• 10 m/s²

Answer explanation

To find acceleration, use the formula: acceleration = (final velocity - initial velocity) / time. Here, acceleration = (20 m/s - 0 m/s) / 4 s = 5 m/s². Thus, the correct answer is 5 m/s².