T-bird Physics Test: Newton's 2nd Law And Horizontally Launched Projectiles

1. The force required to accelerate a 2.0 kg mass at 4m/s² is

6 N

2 N

8 N

16 N

The force required to accelerate a mass is given by the equation F = m * a, where F is the force, m is the mass, and a is the acceleration. In this case, the mass is 2.0 kg and the acceleration is 4 m/s^2. Plugging these values into the equation, we get F = 2.0 kg * 4 m/s^2 = 8 N. Therefore, the correct answer is 8 N.

Explanation

The force required to accelerate a mass is given by the equation F = m * a, where F is the force, m is the mass, and a is the acceleration. In this case, the mass is 2.0 kg and the acceleration is 4 m/s^2. Plugging these values into the equation, we get F = 2.0 kg * 4 m/s^2 = 8 N. Therefore, the correct answer is 8 N.

2. What force will be needed to accelerate an 8 kg mass at the same acceleration as a 4 kg mass?

The amount of force does not change

The force should double

It will take half as much force

The force needs to be 4x's as much

When two objects with different masses are accelerated at the same rate, the force required is directly proportional to the mass. In this case, the 8 kg mass is twice as heavy as the 4 kg mass. Therefore, according to Newton's second law of motion (F = ma), the force required to accelerate the 8 kg mass at the same acceleration as the 4 kg mass should be double.

Explanation

When two objects with different masses are accelerated at the same rate, the force required is directly proportional to the mass. In this case, the 8 kg mass is twice as heavy as the 4 kg mass. Therefore, according to Newton's second law of motion (F = ma), the force required to accelerate the 8 kg mass at the same acceleration as the 4 kg mass should be double.

3. In the graph below, the acceleration of an object is plotted against the unbalanced force applied. What is the mass of the object?

0.5 kg

2 kg

4 kg

0.2 kg

The mass of an object can be determined by dividing the unbalanced force applied to it by its acceleration. In this case, the graph shows that when the unbalanced force is 1 N, the acceleration is 2 m/s^2. By using the formula F = ma, we can rearrange it to solve for mass (m = F/a). Therefore, the mass of the object is 1 N / 2 m/s^2 = 0.5 kg.

Explanation

The mass of an object can be determined by dividing the unbalanced force applied to it by its acceleration. In this case, the graph shows that when the unbalanced force is 1 N, the acceleration is 2 m/s^2. By using the formula F = ma, we can rearrange it to solve for mass (m = F/a). Therefore, the mass of the object is 1 N / 2 m/s^2 = 0.5 kg.

4. A cart is uniformly accelerating from rest.The force on the cart must be

Decreasing

Zero

Constant

Increasing

When a cart is uniformly accelerating from rest, it means that it is experiencing a constant force. This is because according to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it. Since the cart is accelerating uniformly, the force acting on it must also be constant throughout its motion. Therefore, the correct answer is constant.

Explanation

When a cart is uniformly accelerating from rest, it means that it is experiencing a constant force. This is because according to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on it. Since the cart is accelerating uniformly, the force acting on it must also be constant throughout its motion. Therefore, the correct answer is constant.

5. Which of the following has no effect on how far the ball travels horizontally before it strikes the ground?

The mass of the ball

The height of the cliff

The speed with which the ball is thrown

The mass of the ball does not have any effect on how far the ball travels horizontally before it strikes the ground. The horizontal distance traveled by a projectile is determined by the initial velocity and the time of flight, which are influenced by the speed with which the ball is thrown and the height of the cliff. The mass of the ball only affects its vertical motion and how quickly it falls to the ground, but it does not impact the horizontal distance it covers.

Explanation

The mass of the ball does not have any effect on how far the ball travels horizontally before it strikes the ground. The horizontal distance traveled by a projectile is determined by the initial velocity and the time of flight, which are influenced by the speed with which the ball is thrown and the height of the cliff. The mass of the ball only affects its vertical motion and how quickly it falls to the ground, but it does not impact the horizontal distance it covers.

6. A ball is thrown horizontally at a speed of 20m/s from the top of a cliff. If the horizontal speed of the ball is decreased, the time required for the ball to fall 30m will

Decrease

Increase

Remain the same

When a ball is thrown horizontally, its vertical motion is solely determined by the force of gravity. Therefore, the time required for the ball to fall 30m will only depend on the vertical distance and the acceleration due to gravity, both of which remain constant. The horizontal speed of the ball does not affect its vertical motion or the time it takes to fall, so the time required for the ball to fall 30m will remain the same.

Explanation

When a ball is thrown horizontally, its vertical motion is solely determined by the force of gravity. Therefore, the time required for the ball to fall 30m will only depend on the vertical distance and the acceleration due to gravity, both of which remain constant. The horizontal speed of the ball does not affect its vertical motion or the time it takes to fall, so the time required for the ball to fall 30m will remain the same.

7. A ball is tossed straight up in an airplane traveling at a velocity of 500 mi/h due North in a straight line at a constant altitude. When the ball lands in the cabin its position relative to the person who tossed the ball will be

Farther toward the back of the cabin depending upon the plane’s speed

Farther toward the front of the cabin depending on the plane’s speed.

Right back down on the person who tossed it straight upward.

When the ball is tossed straight up in an airplane traveling at a constant velocity, the ball will continue to move with that velocity in the same direction as the airplane. This is due to the principle of inertia, which states that an object in motion will remain in motion with the same velocity unless acted upon by an external force. Therefore, when the ball lands in the cabin, its position relative to the person who tossed it will be right back down on the person who tossed it straight upward.

Explanation

When the ball is tossed straight up in an airplane traveling at a constant velocity, the ball will continue to move with that velocity in the same direction as the airplane. This is due to the principle of inertia, which states that an object in motion will remain in motion with the same velocity unless acted upon by an external force. Therefore, when the ball lands in the cabin, its position relative to the person who tossed it will be right back down on the person who tossed it straight upward.