Physics Midterm #3: Modules 7-9
An acceleration constraint says that in some circumstances
The magnitude of the accelerations of two objects have to be equal.
A box is lifted straight upward by a wire. If the tension in the wire is 116 N and the acceleration of the crate is 0.75 m/s2 upward, what is the mass of the crate?
11 kg
A toy car moves around a circular track at constant speed. It suddenly doubles its speed — a change of a factor of 2. As a result, the centripetal acceleration changes by a factor of
4
Two forces for which Newton's Third Law applies are called
Action/ Reaction Pair
Two forces for which Newton's Third Law applies are called
Action/Reaction Pair
You're on a "Loop the Loop" roller coaster. where do you feel the heaviest
Bottom
In uniform circular motion there's no acceleration because the speed is constant.
False
In uniform circular motion, after a full circle all forces cancel each other and therefore the net force is zero
False
A car with mass 1500 kg driving at constant speed makes a left turn without sliding. Which forces are acting on the car
Gravity, Normal Force, Static Friction
Is the motion on a "Loop the Loop" roller coaster uniform circular motion?
No
A race car driver is taking an un-banked curve while accelerating her car. Which forces are acting on the car?
Normal, static friction, gravity and the force provided by the engine
An ice hockey puck is tied by a string to a stake in the ice. The puck is then swung in a circle. What force or forces does the puck feel?
One or more of our familiar forces pulling inward
For uniform circular motion, the net force
Points toward the center of the circle.
When accelerating slowly from a stop sign, we can say that the propulsion force on a car is due to
Static Friction
The propulsion force on a car is due to
Static friction
A rope is tied to the wall. You pull on it with a force of 100 N. The tension in the rope is T1. Now you play tug-of-war: a second person holds the other end of the rope and you both pull with a force of 100 N in opposite directions. The tension in the rope is now T2. Which of the following is true?
T1=T2
An ice hockey puck is tied by a string to a stake in the ice. The puck is then swung in a circle. What force is producing the centripetal acceleration of the puck?
Tension in the string
A mosquito runs head-on into a truck. Which is true during the collision?
The magnitude of the mosquito's acceleration is larger than that of the truck.
A mosquito runs head-on into a truck. Splat! Which is true during the collision?
The mosquito exerts the same force on the truck as the truck exerts on the mosquito.
