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Which situation describes a non-contact force acting on an object?(1 point)

Responses

a person closing a door
a person closing a door

a person picking up a textbook
a person picking up a textbook

a person cutting an apple with an apple slicer
a person cutting an apple with an apple slicer

a person pouring water out of a pitcher

7 answers

The situation that describes a non-contact force acting on an object is not present in the provided options. Non-contact forces, such as gravitational force, electromagnetic force, or magnetic force, do not require physical contact to act on an object. All the examples given involve contact forces, where an object interacts directly with another object through touch.

If you want an example of a non-contact force, it would typically be something like an object being attracted to the Earth due to gravity, or a magnet attracting a metal object without direct contact.

In which of these situations would an object have the greatest momentum?(1 point)
Responses

An object with a large mass is moving slowly.
An object with a large mass is moving slowly.

An object with a small mass is moving slowly.
An object with a small mass is moving slowly.

An object with a large mass is moving quickly.
An object with a large mass is moving quickly.

An object with a small mass is moving quickly.

Momentum is calculated using the formula:

\[ \text{Momentum} = \text{mass} \times \text{velocity} \]

To have the greatest momentum, we need to consider both mass and velocity.

Among the given options:

  1. An object with a large mass is moving slowly.
  2. An object with a small mass is moving slowly.
  3. An object with a large mass is moving quickly.
  4. An object with a small mass is moving quickly.

The situation with an object with a large mass moving quickly (option 3) would have the greatest momentum, since both the mass and the velocity are relatively high compared to the other scenarios.

A force applied to an object at rest causes the object to move. According to Newton’s first law, what must be true of the force?(1 point)
Responses

The force is unbalanced.
The force is unbalanced.

The force is stronger than gravity.
The force is stronger than gravity.

The force comes from behind the object.
The force comes from behind the object.

The force is stronger than inertia.

According to Newton’s first law of motion, an object at rest will remain at rest unless acted upon by an unbalanced force. Therefore, for a force applied to an object at rest to cause it to move, the correct response is:

The force is unbalanced.

This means that the applied force must overcome any opposing forces (like friction or gravity) to cause the object to accelerate and start moving.

Shot put is a track-and-field event in which athletes propel a metal shot, or ball, by pushing it away from their shoulder. In junior events, shots of different sizes are used for different categories of competitors.

The shot masses and forces applied for four competitors are shown. Which shot will have the greatest acceleration?

(1 point)
Responses

6 kg and 30 N
6 kg and 30 N

5 kg and 30 N
5 kg and 30 N

5 kg and 40 N
5 kg and 40 N

4 kg and 40 N

To find out which shot will have the greatest acceleration, we can use Newton's second law of motion, which states:

\[ \text{Acceleration} (a) = \frac{\text{Force} (F)}{\text{Mass} (m)} \]

We will calculate the acceleration for each competitor using the provided mass and force:

  1. 6 kg and 30 N: \[ a = \frac{30 , \text{N}}{6 , \text{kg}} = 5 , \text{m/s}^2 \]

  2. 5 kg and 30 N: \[ a = \frac{30 , \text{N}}{5 , \text{kg}} = 6 , \text{m/s}^2 \]

  3. 5 kg and 40 N: \[ a = \frac{40 , \text{N}}{5 , \text{kg}} = 8 , \text{m/s}^2 \]

  4. 4 kg and 40 N: \[ a = \frac{40 , \text{N}}{4 , \text{kg}} = 10 , \text{m/s}^2 \]

Comparing the accelerations:

  • 6 kg and 30 N: 5 m/s²
  • 5 kg and 30 N: 6 m/s²
  • 5 kg and 40 N: 8 m/s²
  • 4 kg and 40 N: 10 m/s²

The shot with a mass of 4 kg and a force of 40 N will have the greatest acceleration of 10 m/s².