Physics Unit 2 Forces Quiz

Which object has more inertia and why? A bowling ball at rest or a high-speed soccer ball?

• Bowling Ball because it has more mass.

• Soccer Ball because it has more mass.

• Soccer Ball because it is moving faster.

• Bowling Ball because it is not moving.

Answer explanation

Inertia is Newton's First law. It states that mass is the measure of an object's resistance to the change in motion. The actual motion does not matter.

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According to Newton's __________ law of motion, an object with less mass will experience a greater acceleration if a constant force is applied to the object.

• First

• Second

• Third

• Fourth

Answer explanation

Newton's second law states F=ma. If you reduce the mass but keep the force the same, then the object must have a higher acceleration.

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A 1.50 kg ball is kicked and accelerates at a rate of 4.25 m/s^2. What is the force that was applied to the ball? Ignore all other forces.

• 2.83N

• 6.38N

• 5.75N

• 14.7N

Answer explanation

F = ma

F = (1.5)(5.24) = 6.38N

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The unit named after Issac Newton (N) is equivalent to which units?

• kg m/s

• kg m/s^2

• m/s^2

• kg m/s

Answer explanation

According to Newton's 2nd law,F=ma. Therefore, N=kg*m/s^2

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A cat's motion is described by this image. What is the magnitude of the net force it experiences?

• 490N

• 701N

• 346.6N

• 205.8N

Answer explanation

This was vector addition.

The net y component was (400-150) = 250N

The net x component was (250-10) = 240N

We can combine them using the Pythagorean theorem

The hypotenuse is the magnitude, which is 346.6N

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Draw the force vectors of gravity between the Earth and the moon

Answer explanation

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What is the weight of a 75kg person on Earth? What would their weight be if they were on the moon (moon has an acceleration due to gravity of 1.63 m/s^2

• 75 N, 46 N

• 735 N, 122.25 N

• 10 N, 1.63 N

• 7.5 N, 46 N

Answer explanation

Use Newton's second law for both questions.

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An astronaut weighs 685 N on Earth. What would the astronaut's weight be on Jupiter where g = 25.9 m/s^2? HINT: This is a two step problem.

• 2.70 N

• 69.9 N

• 1810 N

• 17,700 N

Answer explanation

This was a two step problem.

1. Calculate the mass of the astronaut. He weighs 685N on Earth. F=ma therefore, m=F/a.

The acceleration due to gravity on Earth is 9.8, therefore m=(685/9.8)=69.9kg

2. Calculate the force of gravity on Jupiter. F = ma

F = (69.9)*(25.9)=1810N

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• 1,200N

• 604N

• 447N

• 305N

Answer explanation

This was vector addition.

The net vertical component were just the force of gravity, which was 200N.

The net horizontal components was 700-300=400N.

We combine them using the Pythagorean theorem to solve for the hypotenuse.

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Suppose half of Earth's mass disappeared but the radius remained the same. What would be the new acceleration due to gravity on the surface of the Earth?

• 19.6 m/s^2

• 12 m/s^2

• 4.9 m/s^2

• 9.8 m/s^2

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