Forces 1
A force can be defined as....
A push or pull
Is air resistance a contact or non-contact force?
contact
Is gravity a contact or non-contact force?
Is it a push or a pull force?
Non-contact
Pull
True or False:
An object travelling at a constant speed and direction has no forces acting on it.
False - the forces acting on it are balanced
the total (overall) force acting on an object
The units force is measured in is.....
Newtons
List three contact forces and three non-contact forces.
Contact: applied, friction, air resistance, buoyancy, elastic, tension.
Non-contact: gravity, magnetic, static electricity
What is the formula to calculate weight?
What can increase an object's weight?
w = m x g
Objects with more mass have more weight. A greater gravitational pull will also increase weight acting on an object.
What are the units for weight?
A falling object has a weight of 200N and experiences 100N of air resistance. Calculate its net force.
200 - 100 = 100N Downward
Force is a vector, so it is represented by an arrow. Force always has two components....
1. Magnitude
2. Direction
Explain the difference between balanced and unbalanced forces.
Balanced forces are those that are equal in magnitude but opposite in direction. The net force of balanced forces is zero. Objects acted upon by balanced forces stay at rest or move at a constant velocity. Unbalanced forces are forces that are not equal in magnitude and may or may not act in the same direction.
Define gravity
An attractive force between any two objects that have mass
Explain the difference between mass and weight
Mass is the amount of matter in an object and remains constant regardless of location. Weight, on the other hand, is the force exerted on an object due to gravity, and it can change depending on the gravitational field
A object is being pushed to the right with 10N of applied force. There is 5N of friction acting on the object. Calculate the net force.
10 - 5 = 5N Right
Explain why an object would take longer to slide down a surface of sandpaper compared to a surface of smooth, waxed wood.
Smooth, waxed wood has less friction.
Explain how you could get a book resting on a ramp to begin to move.
Venus has a gravitational acceleration of of 8.9m/s/s. Calculate the weight of an 8kg rover on Venus.
71.2N
Gabrielle and Sarah are investigating what could happen to a passenger in a car collision. A marble is carefully balanced on the trolley. The trolley is then released so it can roll down a ramp at different angles to change its speed. When the trolley hits the bottom of the ramp and stops suddenly, the marble flies off the cart. The distance the marble travels is measured using a ruler.
Identify the independent variable.
Identify the dependent variable.
Independent: Angle of the ramp (speed of the trolley)
Dependent: Distance the marble travels measured using a ruler.
Explain what would happen if the air resistance of a falling object becomes balanced with its weight.
If the forces are balanced on a falling object, it will fall at a constant speed in a constant direction.
Explain terminal velocity
When an object's air resistance equals the gravitational pull on a falling object, it experiences terminal velocity. This is when the forces are balanced and the object then falls at a constant speed.
Recall Newton's First Law of Motion
an object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Would it be easier for a rocket to take off from the Earth or the moon? Justify your anser.
The moon because it has less mass. Therefore, it has a weaker gravitational field strength.
A car is driving along at a constant speed and direction. The force pushing the car forward is thrust, while the force acting in the opposite direction is drag.
a. Draw a force diagram to represent the forces acting on the car if it were to start to accelerate.
b. Explain whether the forces acting on the car as it speeds up are balanced or unbalanced.
a. Bigger thrust arrow
b. The forces acting on the car as it speeds up are unbalanced. When forces act on an object in opposite directions and are the same size, they are balanced. However, as the car speeds up the force moving it forward is larger than the force holding it back so it is unbalanced.
Calculate the net force of an object that is being pushed to the right by two people with a force of 10N and 15N, is experiencing friction that has a force of 5N.
10 + 15 = 25
25 - 5 = 20N Right