Newton’s First Law and Motion Concepts: Physics Quiz for Students

Why do we say velocity is a vector and speed is not?

Velocity is a vector because it has both magnitude and direction, while speed only has magnitude and no direction.

How can you be both at rest and also moving at 100,000 km/h at the same time?

You can be at rest relative to a moving object, like the Earth, while moving at high speed relative to another reference point, such as a distant star.

What is the meaning of Σ F = 0?

Σ F = 0 means that the sum of all forces acting on an object is zero, indicating that the object is in equilibrium and not accelerating.

If we push a crate at constant velocity, how do we know how much friction acts on the crate compared to our pushing force?

If the crate moves at constant velocity, the friction force is equal in magnitude and opposite in direction to the pushing force.

If you're in a smooth-riding bus that is going at 50 km/h and you flip a coin vertically, what is the horizontal velocity of the coin in midair?

The horizontal velocity of the coin in midair is also 50 km/h, the same as the bus, due to inertia.

Calculate Emily's average walking speed when she steps 1 meter in 0.5 seconds.

Emily's average walking speed is 2 meters per second (1 meter / 0.5 seconds).

Calculate the average speed of a mouse that runs across a 4-m long room in 0.4 seconds.

The average speed of the mouse is 10 meters per second (4 meters / 0.4 seconds).

Rank the relative velocities of Jogging Johnny as seen by an observer on the ground.

To rank Johnny's velocities, you need specific values for his speed and the speed of the train flatcar.

A ball is released from rest at the left end of a track. Rank the ball at points A, B, C, and D from fastest to slowest.

The ranking depends on the design of the track and the ball's potential and kinetic energy at each point.

Rank the scale readings from greatest to least when a block of iron is suspended by ropes.

The ranking of the scale readings depends on the angles and tension in the ropes.

If the speedometer of a car reads a constant speed of 50 km/h, can you say that the car has a constant velocity?

No, because constant speed does not account for direction; the car must also be moving in a straight line without changing direction to have constant velocity.

Why is running in a zigzag pattern advantageous when being chased by a bear?

Running in a zigzag pattern can make it harder for the bear to predict your path, reducing its ability to catch you despite its mass.

What keeps a space probe going after the rocket no longer pushes it?

The probe continues moving due to inertia, as per Newton's First Law of Motion.

Why do you lurch forward in a bus that suddenly slows?

You lurch forward due to inertia; your body wants to maintain its state of motion when the bus decelerates.

Why do you lurch backward when the bus picks up speed?

You lurch backward due to inertia; your body resists the change in motion as the bus accelerates forward.

What law applies when discussing inertia and motion changes?

Newton's First Law of Motion applies, which states that an object at rest stays at rest and an object in motion stays in motion unless acted upon by a net external force.

Consider a pair of forces, one having a magnitude of 20 N, and the other 12 N. What maximum net force is possible for these two forces?

The maximum net force possible is 32 N (20 N + 12 N) when they act in the same direction.

What is the minimum net force possible with two forces of 20 N and 12 N?

The minimum net force possible is 8 N (20 N - 12 N) when they act in opposite directions.

Why doesn't the rope break when Harry the painter is supported as shown?

The tension in the rope is less than its breaking point when Harry is supported properly.

Why did Harry end up taking his vacation early?

Harry likely tied the rope incorrectly, causing it to bear more weight than its breaking point when tied to the flagpole.

Does Latisha's weight reading change if she raises one foot?

No, the reading remains the same as long as she is still applying the same force on the scale.

What happens to Latisha's weight reading if she stands with one foot on the scale and the other foot on the floor?

The reading on the scale will decrease because only part of her weight is supported by the scale.