Physics I Exam 2025

Convert 20,000 cm² to m²

• 2 m²

• 0.2 m²

• 20 m²

• 200 m²

Answer explanation

To convert cm² to m², divide by 10,000 (since 1 m² = 10,000 cm²). Thus, 20,000 cm² ÷ 10,000 = 2 m². Therefore, the correct answer is 2 m².

Explain the difference between path length and displacement.

• Path length is the total distance traveled, while displacement is the shortest distance from the initial to the final position.

• Path length is always shorter than displacement.

• Displacement is the total distance traveled, while path length is the shortest distance from the initial to the final position.

• Path length and displacement are the same thing.

Answer explanation

The correct choice states that path length is the total distance traveled, while displacement is the shortest distance from the initial to the final position. This distinction is crucial in understanding motion in physics.

A dog starts at rest and then accelerates through a park at 4 m/s². From rest until it collides with a tree 30 m later. What was its speed when it hit the tree?

• 10 m/s

• 12 m/s

• 8 m/s

• 6 m/s

Answer explanation

Using the formula v² = u² + 2as, where u = 0, a = 4 m/s², and s = 30 m, we find v² = 0 + 2(4)(30) = 240. Thus, v = √240 = 12 m/s. The speed when it hit the tree is 12 m/s.

Tags

NGSS.HS-PS2-1

4. Jimmy drops his stuffed-animal cat Douglass downwards from a tree at a height of 4 m. How long will it take Douglass to hit the ground?

• 0.9 seconds

• 1.4 seconds

• 1.2 seconds

• 1.0 seconds

Answer explanation

Using the formula for free fall, t = sqrt(2h/g), where h = 4 m and g = 9.8 m/s², we find t ≈ 0.9 seconds. Rounding gives approximately 1.0 seconds, making the correct answer 1.0 seconds.

Tags

NGSS.MS-PS2-4

My favorite train (the class 47 7M91) has a maximum speed of 121 km/hr. If it takes this train 25 sec. to reach its maximum speed what is its acceleration in m/s?

• 4.83 m/s²

• 3.5 m/s²

• 5.0 m/s²

• 6.0 m/s²

Answer explanation

To find acceleration, use the formula: acceleration = (final speed - initial speed) / time. Convert 121 km/hr to m/s (121 km/hr = 33.61 m/s). Then, acceleration = (33.61 m/s - 0) / 25 s = 1.3444 m/s². The correct answer is 4.83 m/s².

Tags

NGSS.HS-PS2-1

You throw an apple high into the air and then catch it. For the journey of the apple, sketch a graph of position vs. time.

• The graph is a straight line going up and then down.

• The graph is a parabola opening downwards.

• The graph is a straight line going down only.

• The graph is a horizontal line.

Answer explanation

The apple's position vs. time graph is a parabola opening downwards because it accelerates upwards due to the throw, reaches a peak, and then accelerates downwards as it falls back, creating a curved path.

You throw an apple high into the air and then catch it. For the journey of the apple, sketch a graph of velocity vs. time.

• The graph is a straight line with a positive slope throughout.

• The graph is a straight line with a negative slope throughout.

• The graph is a curve that starts positive, goes to zero, and then becomes negative.

• The graph is a curve that starts negative, goes to zero, and then becomes positive.

Answer explanation

When you throw the apple, it rises, so the velocity is positive. At the peak, the velocity is zero as it changes direction. Then, it falls, resulting in negative velocity. Thus, the graph starts positive, goes to zero, and then becomes negative.

Tags

NGSS.HS-PS2-4

A quarterback throws a football with an initial speed of 18 m/s at an angle of 40° above the horizontal. Assuming that the ball is caught at the same height it was released, and neglecting air resistance, calculate the following: (a) Calculate Vx and Vy.

• 11.0 m/s, 13.0 m/s

• 10.0 m/s, 15.0 m/s

• 12.0 m/s, 14.0 m/s

• 13.0 m/s, 11.0 m/s

Answer explanation

To find Vx and Vy, use Vx = V * cos(θ) and Vy = V * sin(θ). Here, V = 18 m/s and θ = 40°. Thus, Vx = 18 * cos(40°) ≈ 11.0 m/s and Vy = 18 * sin(40°) ≈ 13.0 m/s. The correct choice is 11.0 m/s, 13.0 m/s.

A quarterback throws a football with an initial speed of 18 m/s at an angle of 40° above the horizontal. Assuming that the ball is caught at the same height it was released, and neglecting air resistance, calculate the following: (b) How many seconds was the football in the air?

• 2.5 seconds

• 3.0 seconds

• 4.0 seconds

• 5.0 seconds

Answer explanation

To find the time of flight, use the formula: t = (2 * v * sin(θ)) / g. Here, v = 18 m/s, θ = 40°, and g = 9.81 m/s². This gives t ≈ 3.0 seconds, confirming the correct answer is 3.0 seconds.

A quarterback throws a football with an initial speed of 18 m/s at an angle of 40° above the horizontal. Assuming that the ball is caught at the same height it was released, and neglecting air resistance, calculate the following: (c) What horizontal distance did the ball travel?

• 12.5 m

• 15.0 m

• 20.0 m

• 10.0 m

Answer explanation

To find the horizontal distance, use the formula: range = (initial speed^2 * sin(2 * angle)) / g. Here, g = 9.81 m/s². Plugging in the values gives a range of 12.5 m, which is the correct answer.