Additional: Force, Mass And Acceleration

1. If an object is moving at a constant velocity, the forces on it are:-

Unequal

Resolved

Forwards

Balanced

Opposite

If an object is moving at a constant velocity, it means that there is no acceleration acting on it. According to Newton's first law of motion, an object will continue to move at a constant velocity unless acted upon by an external force. In this case, since the object is moving at a constant velocity, it implies that the forces acting on it are balanced. This means that the forces pushing or pulling the object in different directions are equal in magnitude and opposite in direction, resulting in a net force of zero and allowing the object to maintain a constant velocity.

Explanation

If an object is moving at a constant velocity, it means that there is no acceleration acting on it. According to Newton's first law of motion, an object will continue to move at a constant velocity unless acted upon by an external force. In this case, since the object is moving at a constant velocity, it implies that the forces acting on it are balanced. This means that the forces pushing or pulling the object in different directions are equal in magnitude and opposite in direction, resulting in a net force of zero and allowing the object to maintain a constant velocity.

2. If a bicycle and rider of mass 80kg is accelerating at 1.5m/s²the force pushing it is:-

0.02N

81.5N

120N

120m

120kg

The force pushing the bicycle and rider can be calculated using Newton's second law, which states that force is equal to mass multiplied by acceleration. In this case, the mass of the bicycle and rider is given as 80kg, and the acceleration is given as 1.5m/s2. Therefore, the force pushing the bicycle and rider is 80kg * 1.5m/s2 = 120N.

Explanation

The force pushing the bicycle and rider can be calculated using Newton's second law, which states that force is equal to mass multiplied by acceleration. In this case, the mass of the bicycle and rider is given as 80kg, and the acceleration is given as 1.5m/s2. Therefore, the force pushing the bicycle and rider is 80kg * 1.5m/s2 = 120N.

3. To cause an object that is moving to slow down you must:-

Balance the forces

Apply a resultant force in the direction of motion

Apply a resultant force in the opposite direction to the motion

Apply a resultant force at right angles to the motion

Make sure the forces are in equilibrium

When an object is moving, it has a certain momentum in a specific direction. In order to slow down this object, a resultant force needs to be applied in the opposite direction to the motion. This force will act against the object's momentum, causing it to decrease and eventually come to a stop. By applying a force in the opposite direction to the motion, the object's speed will decrease, resulting in a slowdown.

Explanation

When an object is moving, it has a certain momentum in a specific direction. In order to slow down this object, a resultant force needs to be applied in the opposite direction to the motion. This force will act against the object's momentum, causing it to decrease and eventually come to a stop. By applying a force in the opposite direction to the motion, the object's speed will decrease, resulting in a slowdown.

4. A seatbelt brings a passenger to a stop from 12m/s in just 2s. If the passenger has a mass of 60kg, what is the force exerted by the seatbelt?

720N

360N

10N

2.5N

0.25N

When a passenger wearing a seatbelt comes to a stop from a velocity of 12m/s in 2 seconds, the deceleration can be calculated using the formula a = (vf - vi) / t, where vf is the final velocity, vi is the initial velocity, and t is the time taken. Plugging in the given values, we get a = (0 - 12) / 2 = -6m/s^2.

The force exerted by the seatbelt can be calculated using the formula F = m * a, where m is the mass of the passenger and a is the acceleration. Plugging in the given mass of 60kg and the calculated acceleration of -6m/s^2, we get F = 60 * -6 = -360N. Since force is a vector quantity, the negative sign indicates that the force is acting in the opposite direction. Therefore, the magnitude of the force exerted by the seatbelt is 360N.

Explanation

When a passenger wearing a seatbelt comes to a stop from a velocity of 12m/s in 2 seconds, the deceleration can be calculated using the formula a = (vf - vi) / t, where vf is the final velocity, vi is the initial velocity, and t is the time taken. Plugging in the given values, we get a = (0 - 12) / 2 = -6m/s^2.

The force exerted by the seatbelt can be calculated using the formula F = m * a, where m is the mass of the passenger and a is the acceleration. Plugging in the given mass of 60kg and the calculated acceleration of -6m/s^2, we get F = 60 * -6 = -360N. Since force is a vector quantity, the negative sign indicates that the force is acting in the opposite direction. Therefore, the magnitude of the force exerted by the seatbelt is 360N.

5. A motorcyclist of mass 250kg accelerates from rest to 20m/s in 4s. What is the force from the engine?

1250N

50N

1000N

5000N

20000N

The force from the engine can be determined using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the mass of the motorcyclist is given as 250kg and the acceleration can be calculated by dividing the change in velocity (20m/s) by the time taken (4s). Therefore, the acceleration is 5m/s^2. Multiplying the mass and acceleration together gives a force of 1250N.

Explanation

The force from the engine can be determined using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the mass of the motorcyclist is given as 250kg and the acceleration can be calculated by dividing the change in velocity (20m/s) by the time taken (4s). Therefore, the acceleration is 5m/s^2. Multiplying the mass and acceleration together gives a force of 1250N.

6. Which of the following conditions have to be true when a parachutist reaches Terminal Velocity

The forces on her must be balanced

Her weight must be greater than air resistance

Her weight must be less than air resistance

Her speed must be greater than her weight

Her speed must be less than air resistance

When a parachutist reaches terminal velocity, the forces on her must be balanced. This means that the force of gravity pulling her down (her weight) is equal to the force of air resistance pushing against her as she falls. When these forces are balanced, the parachutist stops accelerating and reaches a constant speed, which is the terminal velocity. If her weight is greater than air resistance, she would continue to accelerate. If her weight is less than air resistance, she would slow down. So, the only condition that must be true for a parachutist to reach terminal velocity is that the forces on her must be balanced.

Explanation

When a parachutist reaches terminal velocity, the forces on her must be balanced. This means that the force of gravity pulling her down (her weight) is equal to the force of air resistance pushing against her as she falls. When these forces are balanced, the parachutist stops accelerating and reaches a constant speed, which is the terminal velocity. If her weight is greater than air resistance, she would continue to accelerate. If her weight is less than air resistance, she would slow down. So, the only condition that must be true for a parachutist to reach terminal velocity is that the forces on her must be balanced.

7. An aircraft of mass 4T gets 16kN of force from the engines. It's acceleration will be:-

64m/s2

4000m/s2

4m/s2

64000m/s2

250m/s2

The acceleration of an aircraft can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration (F = ma). In this case, the given force is 16kN and the mass of the aircraft is 4T (or 4000kg). Plugging these values into the equation, we get 16kN = 4000kg * a. Solving for acceleration, we find that a = 4m/s^2. Therefore, the correct answer is 4m/s^2.

Explanation

The acceleration of an aircraft can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration (F = ma). In this case, the given force is 16kN and the mass of the aircraft is 4T (or 4000kg). Plugging these values into the equation, we get 16kN = 4000kg * a. Solving for acceleration, we find that a = 4m/s^2. Therefore, the correct answer is 4m/s^2.

8. A lorry accelerates at 6m/s² when the engine provides a resultant force of 48kN. What is the mass of the lorry?

133kg

28800kg

80kg

8000g

8000kg

The mass of an object can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the given resultant force is 48kN and the acceleration is 6m/s^2. Rearranging the formula, we have mass = force/acceleration. Substituting the values, we get mass = 48kN/6m/s^2 = 8000kg. Therefore, the mass of the lorry is 8000kg.

Explanation

The mass of an object can be calculated using Newton's second law of motion, which states that force is equal to mass multiplied by acceleration. In this case, the given resultant force is 48kN and the acceleration is 6m/s^2. Rearranging the formula, we have mass = force/acceleration. Substituting the values, we get mass = 48kN/6m/s^2 = 8000kg. Therefore, the mass of the lorry is 8000kg.

9. If there is a constant resultant force on an object the following will be happening:-

It's acceleration is increasing

It's acceleration is decreasing

It is moving with constant speed

It is moving with constant acceleration

It is stationary

If there is a constant resultant force on an object, it means that the net force acting on the object is constant. According to Newton's second law of motion, F = ma, where F is the net force, m is the mass of the object, and a is the acceleration. Since the force is constant, the acceleration of the object will also be constant. Therefore, the object will be moving with constant acceleration.

Explanation

If there is a constant resultant force on an object, it means that the net force acting on the object is constant. According to Newton's second law of motion, F = ma, where F is the net force, m is the mass of the object, and a is the acceleration. Since the force is constant, the acceleration of the object will also be constant. Therefore, the object will be moving with constant acceleration.

10. Which of the following does NOT affect the thinking distance of a driver.

Drugs

Alcohol

Fog

Speed of the car

Tiredness

Fog does not affect the thinking distance of a driver because thinking distance refers to the distance a vehicle travels while the driver reacts to a situation. Fog may affect visibility, but it does not directly impact the driver's ability to think and react quickly. Other factors such as drugs, alcohol, speed of the car, and tiredness can all impair a driver's thinking distance by affecting their cognitive abilities, reaction time, or judgment.

Explanation

Fog does not affect the thinking distance of a driver because thinking distance refers to the distance a vehicle travels while the driver reacts to a situation. Fog may affect visibility, but it does not directly impact the driver's ability to think and react quickly. Other factors such as drugs, alcohol, speed of the car, and tiredness can all impair a driver's thinking distance by affecting their cognitive abilities, reaction time, or judgment.