Vocabulary
What is produced by net forces on an object? a. acceleration b. pressure c. mass d. friction
What is a. acceleration (also, the combination of all forces on an object is the net force) Acceleration is inversely proportional to mass. A=F/M
T/F: Friction acts in the opposite direction of the force of motion.
What is True-friction depends on the two surfaces and the force pushing those surfaces. Without friction going in the opposite direction, a force would go on forever (or until it hits something).
A 20 N force gives an acceleration of 4.0 m/s squared. What is the objects mass?
What is 5 kg
If I push a 10 kg block with a 20 N force (with no opposing force), how fast will the block acceleration?
What is a=F/m = 2m/s squared
T/F: An object in free fall can have zero acceleration.
What is False-due to air resistance, you would not have zero acceleration in a free fall (you can have a net force at zero in terminal velocity).
This is force per unit area and measured using pascals. a. acceleration b. pressure c. mass d. friction
What is b. pressure (pascals are force per square meters)
How can two objects in free fall that have different masses have the same acceleration and hit the ground at the same time?
What is: the free falling force is gravity (it's weight); however, mass resists acceleration, which is inertia. Therefore, acceleration will be the same.
A 20 N force gives an acceleration of 4.0 m/s squared. What force would be needed to give this same object an acceleration of 1.0 m/s squared?
What is if the mass is 5 kg, then the force to get an acceleration of 1 would have to be 5N because of the formula a=F/m.
If I push a 10 kg block with a 28 N force, but with a 8 N friction force, how fast will the block acceleration?
What is a=F/m = 2m/s squared (in this case you had to figure out the net force by subtracting the friction from the initial force)
Can a liquid be a gas?
What is Yes-because it flows, similar to a liquid.
Terminal speed is of a person parachuting, with the chute open is? a. 150km/h b. 25 km/h c. 5 km/h d. 15 km/h
What is d. 15 km/h
If you move a 40 kg crate with a 200 N force, with friction of 100 N, what will be your acceleration?
What is 2.5 m/s squared. (a=F/m)
An object has a mass of 40 kg and an acceleration of 2.0 m/s squared. What is the force?
What is 80 N
If a 200,000 kg airplane takes off with a force of 20,000 N, what is it's acceleration?
What is .1 m/s squared (a=F/m)
T/F: A skydiver has zero acceleration and no air resistance when he has reached terminal speed.
What is True
T/F: terminal velocity net force is zero.
What is True
T/F: If you stand on a scale with one foot instead of two, your force will be less.
What is False-you will have the same force on the scale.
An object has a mass of 40 kg and an acceleration of 2.0 m/s squared. What will the force be be for a 20 kg object with the same acceleration as above?
What is 40 N (a=F/m)
If a ball is thrown in the air, at the top of its path the net force is?
What is simply its weight (as there is no friction, nor is there acceleration).
If a block is resting on an incline, the friction needed in order for the force not to slide would have to _________? a. decrease b. increase c. remain the same
What is b. increase (also if the incline increases, the support force decreases).
Define terminal speed?
What is terminal speed is the maximum speed of an object when it falls through a fluid. A skydiver reaches terminal speed when the force of air friction equals the weight of the skydiver. Thus, the speed at which the acceleration of a falling object is zero because friction balances the weight. After which, the skydiver falls at a constant rate.
If I hold a 2 N apple in my hand, how will the net force be different than if the apple free falls from a tree?
What is the net force of 2 N in a free fall will be 2 N as there is no friction. But, if I am able to hold a 2 N force in my hand, that means the friction force in my hand would be 2 N in order to hold it at rest, which would be a 0 net force.
If a skydivers weight is 60 kg and has 240 N air resistance, what will the acceleration be?
What is 6 m/s squared. You would multiply kg by gravity (6 x 10=600 for your force down). Then you subtract force down with force up to get your net force (600-240=360). To find teh acceleration you divide the net force by the man's weight (360/ 60).
If a 4500 kg truck is being moved by a force of 9000 N, what would happen to the acceleration of the truck if the mass doubles?
What is it would be cut in half (or decrease).
T/F: It is better to stand on ice than to lay down on ice because you are covering less surface area, which will be less pressure on the ice.
What is False-the more weight distributed over the area, the less overall pressure.