1.
If an object is moving at a constant velocity, the forces on it are:-
Correct Answer
D. Balanced
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 there is a constant resultant force on an object the following will be happening:-
Correct Answer
D. It is 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.
3.
To cause an object that is moving to slow down you must:-
Correct Answer
C. Apply a resultant force in the opposite direction to the motion
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.
If a bicycle and rider of mass 80kg is accelerating at 1.5m/s^{2 }the force pushing it is:-
Correct Answer
C. 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.
5.
A lorry accelerates at 6m/s^{2} when the engine provides a resultant force of 48kN. What is the mass of the lorry?
Correct Answer
E. 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.
6.
An aircraft of mass 4T gets 16kN of force from the engines. It's acceleration will be:-
Correct Answer
C. 4m/s2
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.
7.
A motorcyclist of mass 250kg accelerates from rest to 20m/s in 4s. What is the force from the engine?
Correct Answer
A. 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.
8.
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?
Correct Answer
B. 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.
9.
Which of the following does NOT affect the thinking distance of a driver.
Correct Answer
C. Fog
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.
10.
Which of the following conditions have to be true when a parachutist reaches Terminal Velocity
Correct Answer
A. 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.