Questions and Answers
A car accelerates from 4 meters/second to 16 meters/second in 4 seconds. The car's acceleration is _____ meters/second².
3
How long does the car take to travel 90 miles if it moves with an average speed of 45 miles/hour?
2 hours
At which points in the ball's journey will gravity be the greatest force acting on the ball?
When the ball leaves his hand, when it is up in the air, and when it starts to fall.
What is the primary force that helps suspension bridges use cables to hold their spans up?
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Which of these statements is true the moment Gina presses the gas pedal? Assume the road is flat and level.
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Which force caused the ball to move downhill when James gently releases it at the top of a slope?
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To create a net force of zero on an object with a 33-newton force pointing downward, which force must be applied?
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What can be said about the forces acting on a toy car at the moment Anne applies a force to make it move forward?
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What is the force of the impact when a pitcher throws a softball towards home plate, with a velocity change from 32 meters/second to 0 meters/second over 0.8 seconds?
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What's the acceleration of a ball during a collision if it moves from 0.6 meter/second to -0.4 meter/second in 0.2 seconds?
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If Sully accelerates a snowmobile to a velocity of 16 meters/second over 10 seconds, what's the force exerted by the snowmobile if the total mass is 280 kilograms?
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What should the car's mass be if the carmaker wants to reach an acceleration of 15 meters/second² using the same engine that can achieve 12 meters/second² with a mass of 1,515 kilograms?
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Blake drags 3 boxes 10 meters each with a force of 20 newtons. Sandra drags 4 boxes 12 meters each with a force of 15 newtons. Who does more work and who has more power?
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What are two ways of stating the relationship for calculating power as work divided by time?
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What is the minimum input force needed to lift a bowling ball if Tori applies 70 newtons to a single pulley and adds another pulley for a mechanical advantage of 2?
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How much power does Carter use while pushing a bag full of basketball jerseys with a constant force of 21 newtons over 9 meters in 3 seconds?
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Study Notes
Acceleration and Forces
- A car accelerates from 4 m/s to 16 m/s in 4 seconds, resulting in an acceleration of 3 m/s².
- Average speed of a car traveling 90 miles at 45 mph requires 2 hours for the journey.
- Gravity acts on a ball thrown upwards at three key moments: when released, when at peak height, and when falling back down.
Forces in Motion
- Tension force is the primary force that supports suspension bridges and holds their spans.
- When Gina presses the gas pedal at a green light, the net force on her car is greater than zero in the horizontal direction.
- A ball rolls downhill on a slope due to gravitational force acting on it.
Net Forces and Balanced Forces
- To achieve a net force of zero on an object with a 33 N downward force, an additional 33 N force must be applied upward.
- When Anne pushes a toy car, the forces acting on it become unbalanced, leading to movement.
Momentum and Impact Forces
- The impact force on a 0.2 kg softball reaching 0 to 32 m/s in 0.8 seconds can be calculated using F = ma.
- A ball colliding with a wall changes its velocity from 0.6 m/s to -0.4 m/s in 0.2 seconds, resulting in an acceleration of -5.0 m/s².
Work, Power, and Efficiency
- To determine the force required for a snowmobile weighing 280 kg to accelerate from 10 m/s to 16 m/s in 10 seconds, apply F = ma, resulting in 168 N.
- A car designed for a maximum acceleration of 12 m/s² with a mass of 1,515 kg would need its mass reduced to 1,212 kg to achieve an acceleration of 15 m/s².
- Blake does less work than Sandra over a longer time, resulting in Blake’s power being less than Sandra’s despite dragging boxes.
Power Calculations
- The power formula is given as power = work ÷ time, leading to alternative formulations: work = power × time and time = work ÷ power.
- To lift a bowling ball with a pulley system providing a mechanical advantage of 2, Tori would need a minimum input force of 35 N when applying 70 N on a single pulley.
Practical Applications of Power
- Carter’s constant force of 21 N used to push a bag 9 meters over 3 seconds results in a power output of 63 watts.
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Description
Test your knowledge on acceleration, forces in motion, and the impact of gravity. This quiz covers various scenarios involving net forces, balanced forces, and momentum. Perfect for students studying physics concepts related to motion and forces.
