1.
Friction acts in a direction __________ to the direction of an object's motion
Correct Answer
B. Opposite
Explanation
Friction acts in the opposite direction to the direction of an object's motion. When an object moves, friction acts in the opposite direction to the motion, trying to slow down or stop the object's movement. This is because friction is a force that opposes the relative motion between two surfaces in contact. Therefore, the correct answer is "opposite".
2.
Unless an object at rest is acted upon by a force, it stays at rest due to its
Correct Answer
B. Inertia
Explanation
Inertia is the property of an object to resist any change in its state of motion. According to Newton's first law of motion, an object at rest will remain at rest unless acted upon by an external force. This is because the object possesses inertia, which causes it to resist any change in its state of rest. Therefore, unless a force is applied to overcome the object's inertia, it will continue to stay at rest.
3.
A 10-kg ball is accelerated 500m/s (squared) by a force of...
Correct Answer
A. 5000 N
Explanation
The correct answer is 5000 N because the force required to accelerate an object can be calculated using the formula F = m*a, where F is the force, m is the mass, and a is the acceleration. In this case, the mass of the ball is 10 kg and the acceleration is 500 m/s^2. Plugging these values into the formula, we get F = 10 kg * 500 m/s^2 = 5000 N. Therefore, a force of 5000 N is required to accelerate the 10-kg ball at a rate of 500 m/s^2.
4.
The momentum of a 1500-kg car traveling at a velocity of 10 m/s is ....
Correct Answer
D. 15,000 kg x m/s
Explanation
The momentum of an object is calculated by multiplying its mass by its velocity. In this case, the mass of the car is given as 1500 kg and its velocity is given as 10 m/s. Therefore, the momentum of the car is 1500 kg multiplied by 10 m/s, which equals 15,000 kg x m/s.
5.
A (n) ______________ can cause an objects motion to change
Correct Answer
A. Unbalanced force
Explanation
An unbalanced force can cause an object's motion to change. When there is an unbalanced force acting on an object, it means that the forces acting on the object are not equal in magnitude and opposite in direction. This imbalance causes the object to accelerate or decelerate, or change its direction of motion. In contrast, a balanced force occurs when the forces acting on an object are equal in magnitude and opposite in direction, resulting in no change in motion. Inertia and mass are properties of an object and do not directly cause a change in motion.
6.
The amount of matter in an object is called its
Correct Answer
D. Mass
Explanation
Mass refers to the amount of matter in an object. It is a fundamental property of an object and is independent of its location or the force acting upon it. Weight, on the other hand, is the force exerted on an object due to gravity and can vary depending on the gravitational pull. Inertia is the resistance of an object to changes in its motion. Therefore, the correct answer is mass, as it specifically relates to the amount of matter in an object.
7.
Newtons second law of motion states the relationship of mass, acceleration and force. It says that....
Correct Answer
C. Force equals mass times acceleration
Explanation
Newton's second law of motion states that the force acting on an object is directly proportional to the mass of the object and the acceleration it experiences. In other words, the force equals the product of mass and acceleration. This means that the greater the mass of an object or the greater the acceleration it experiences, the greater the force acting on it will be. Conversely, if the mass or acceleration decreases, the force will also decrease. Therefore, the correct answer is "force equals mass times acceleration."
8.
A(n) ___________ causes objects to move in a circle
Correct Answer
A. Centripetal force
Explanation
Centripetal force is the correct answer because it is the force that causes objects to move in a circle. It acts towards the center of the circle and keeps the object in circular motion. This force is necessary to counterbalance the tendency of the object to move in a straight line due to inertia. Without centripetal force, objects would continue in a straight line instead of following a circular path.
9.
An object in free fall _____________ until it reaches terminal velocity
Correct Answer
C. Accelerates
Explanation
An object in free fall accelerates until it reaches terminal velocity. This is because in free fall, the object is only under the influence of gravity, which causes it to accelerate downwards. As the object falls, its speed increases until it reaches a point where the upward force of air resistance balances out the downward force of gravity. At this point, the object stops accelerating and reaches a constant velocity known as terminal velocity. Therefore, the correct answer is "accelerates".
10.
Forces can be added together on if they are acting on different objects.
Correct Answer
B. False
Explanation
Forces can be added together only if they are acting on the same object. When forces act on different objects, they cannot be added together because they are exerted on separate entities and have different effects. Therefore, the statement is false.
11.
According to Newton;s second law of motion, acceleration increases as force increases, if mass stays the same.
Correct Answer
A. True
Explanation
According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. This means that if the force acting on an object increases, and its mass remains constant, the acceleration of the object will also increase. Therefore, the statement that acceleration increases as force increases, if mass stays the same, is true.
12.
The force exerted by gravity is stronger if two objects are closer.
Correct Answer
A. True
Explanation
The statement is true because gravity is a force that attracts objects towards each other. The strength of the gravitational force between two objects depends on their masses and the distance between them. As the distance between two objects decreases, the force of gravity between them increases. Therefore, if two objects are closer to each other, the force exerted by gravity will be stronger.
13.
The force of friction acts between all objects in the universe.
Correct Answer
B. False
Explanation
The statement that the force of friction acts between all objects in the universe is false. Friction is a force that opposes the relative motion between two surfaces in contact. While friction is a common force that we experience in our daily lives, it is not present between all objects in the universe. In space, for example, where there is no atmosphere or surfaces in contact, there is no friction. Additionally, friction only occurs when there is relative motion or an attempt to move between two surfaces, so it does not act between all objects.
14.
A satellite in orbit around Earth is always falling toward Earth.
Correct Answer
A. True
Explanation
A satellite in orbit around Earth is constantly being pulled towards Earth by gravity. However, it is also moving forward with enough speed that it continuously falls around the Earth instead of crashing into it. This is known as freefall or gravitational attraction. As a result, the statement is true.
15.
Jake and Tom want to see who is strogest, so they got a rope and decided to play tug-o-war. Both boys pulled at the rope with all of their strength, but neither of them moved.
This is called unbalanced force.
Correct Answer
B. False
Explanation
This statement is false because the scenario described in the question does not involve unbalanced forces. Unbalanced forces occur when there is a net force acting on an object in a particular direction, causing it to accelerate or move. In this case, both boys pulled with equal strength and neither of them moved, indicating that the forces were balanced.
16.
Patty was walking very quickly through the cafeteria with her tray full of food when she tripped over a broomstick and flew forward along with all of her food.
This is an example of Newton's first law of motion which states, "...an obect in motion will stay in motion..."
Correct Answer
A. True
Explanation
This scenario aligns with Newton's first law of motion, also known as the law of inertia. According to this law, an object in motion will continue to move in the same direction and at the same speed unless acted upon by an external force. In this case, Patty was walking quickly through the cafeteria (in motion) when she tripped over a broomstick (external force). As a result, she flew forward along with all of her food, demonstrating the concept of inertia. Therefore, the answer is true.