PHYS 110 TEST 2
Referring to the previous question, what is the centripetal acceleration of the object?
50.3 m/s^2
Earth exerts a gravitational force of 7000 N on one of the communications satellites. What force does the satellite exert on Earth, if it does?
7000 N
A baseball is hit with a vertical speed of 40 m/s and a horizontal speed of 30 m/s. How long will the ball remain in the air?
8S
Which one of the following is true regarding kinetic and potential energies of a body?
A body can have kinetic and potential energies at the same time.
If a body is traveling around a circular track at a constant speed, which one the following is true?
A net force is acting on it and it is directed towards the center
What is the gravitational force of attraction between two spherical metal balls, each having a mass of 0.20-kg separated by a distance of 80 cm ? ( NOTE : 4.16875E-12 = 4.16875X10-12 )
4.16875E-12 N
The direction of the centripetal force on a body in a circular motion is:
Towards the center of the circle
Airbags in cars are used to reduce:
Force
Which one of the following is correct regarding gravitational force?
Gravitational force is a vector quantity.
The acceleration due to gravity of the Earth is approximately equal to ___________m/s2 at a distance of 5 times Earth's radius from the center of the Earth.
0.40 m/s2
If the momentum of a body changes from 7kg.m/s to 12-kg.m/s in a time of 5 seconds, what impulse is acting on the body?
5 kg.m/s
Which of the following will cause the largest change-in-momentum of an object? A force of ____ acting for ____.
1000 N.....1 S
A box of mass 500g is dropped from a height of 25 m above the ground. If the ground level is taken as a reference (a point of zero gravitational potential energy), what is the gravitational potential energy of the box at the height of 25m? (Use acceleration due to gravity near the surface of the Earth as 10 m/S^2).
125 Joules
Referring to the previous question, what is the Mechanical Energy of the box when it hits the floor ( at h=0-m )? (Hint: Use the Law of Conservation of Mechanical Energy).
125-Joules
What impulse is needed to stop a 1500-kg car traveling at 10 m/s?
15000 kg.m/s
A projectile was launched at a horizontal velocity of 5.0 m/s and a vertical upward velocity of 30m/s. What are the horizontal and vertical velocities of the projectile 5 seconds later? (assume there is no force acting on the projectile in the horizontal direction)
20 m/s vertical (downward) and 5 m/s horizontal
If a person's weight on the Earth is 800N, what will the person's weight be at a distance equal to 2 times Earth's radius? ( HINT: Find "g" at a distance of 2R, where R is the radius of the Earth) and use w =mg. Also, use g=10m/s^2 at "R" (on the surface of the Earth).
200 N
An object of mass 2.0 kg is attached to a string and whirled around a horizontal circular path of radius 10m. If it takes the object 2.8 seconds to make one cycle (to move once in the circle), the speed of the object is:
22.4 m/s
A synchronous satellite has a period of:
24 hours
Two balls of masses 1kg and 2 kg are rolling on top of a frictionless table in opposite directions with velocities of 2m/s and 3m/s respectively. (Assume there is no net external force acting on the balls. What is the total momentum of the two balls before they collide?
*wrong* 8 kg. m/s
Two men jump from the same height to the ground, one of them falls stiff-legged on mattress while the other one falls on concrete stiff-legged. The one who fell on concrete gets hurt more than the one who fell on mattress. Which one of the following is is the best explanation for the difference from the point of view of physics using impulse?
*wrong* There is a greater impulse on the one who falls on concrete and that is why it hurts more
Which one of the following is correct?
Change in momentum of a body is equal to the impulse acting on the body causing the change.
Which one of the following is a capacity of doing work?
ENERGY
Which one of the following statements is incorrect?
Impulse and force mean the same thing.
Which of the following is a unit of energy?
Joule
Which one of the following is true regarding the gravitational force between two bodies?
The gravitational force between two bodies changes inversely as the square of the distance between them.
When a rifle is fired, the rifle recoils back as the bullet moves forward. Which one of the following principles of Physics explains best the recoil of the gun?
The law of conservation of momentum.
One of the following is incorrect regarding a projectile motion. Which one?
The vertical acceleration of a projectile motion is zero.
