Collisions Between Objects with equal Masses
One marble is moving and collides with a stationary marble. Which of these statements is true?
A- each marble exerts a force on the other, and two forces are the same in magnitude and direction
B- Each marble exerts a force on the other, and the two forces are equal and in opposite directions
C- The moving marble exerts a force on the stationary marble, but the stationary marble does not exert a force on the moving marble.
D- Each marble exerts a force on the other, and the two forces are proportional to the masses of the marbles.
B- Each marble exerts a force on the other, and the two forces are equal and in opposite directions
During a baseball game, a hitter strikes the ball with a bat. When this happens, the ball and the bat exert a force on each other. Why does the ball accelerate away from the bat more than the bat accelerates away from the ball?
A- The bat exerts more force than the ball because the batter is exerting a force on the bat as it hits the ball.
B- The ball has less mass, so the equal force on the ball the bat causes greater acceleration of the ball.
C- The ball has greater velocity before the collision, so the force affects the ball more than it affects the bat.
E- The ball has less mass, so it exerts less force on the bat.
B- The ball has less mass, so the equal force on the ball the bat causes greater acceleration of the ball.
The front of a car is designed to crumple during a crash. What is the purpose of this?
A- to decrease the amount of time it takes for the collision to occur, increasing the acceleration of the car
B- to increase the amount of time it takes for the collision to occur, decreasing the acceleration of the car
C- to increase the amount of time it takes for the collision to occur, decreasing the force of the collision
D- to decrease the mass of the car, decreasing the force of the collision.
B- to increase the amount of time it takes for the collision to occur, decreasing the acceleration of the car
Sayid has two carts with masses of 200 g and 400 g. He pushes the smaller cart toward the larger cart and they collide. The smaller cart rebounds back in the direction it came from. He measures the force on the smaller cart from the larger cart to be 800N.
What was the magnitude (size) of the acceleration of the smaller cart? Use the formula A = f/m, or acceleration = force divided by mass
4 m /s (800 N divided by 200 g)
One marble is moving and collides with a stationary marble. Which of these statements is true?
A- The moving marble exerts a force on the stationary marble, but the stationary marble does not exert a force on the moving marble.
B- Each marble exerts a force on the other, and the two forces are proportional to the masses of the marbles.
C- Each marble exerts a force on the other, and the two forces are equal and in opposite direction.
D- Each marble exerts a force on the other, and two forces are the same in magnitude (size) and direction.
C- Each marble exerts a force on the other, and the two forces are equal and in opposite direction.
A soccer player kicks a ball. The player’s foot exerts a force on the ball. The ball exerts a force on the foot. Why don’t the forces cancel out to result in a net force of zero?
A- the forces are exerted on different objects, and neither force is zero.
B-The ball moves before the forces can cancel out.
C- The force on the ball is greater than the force on the foot.
D- The forces become unbalanced due to air resistance.
A- the forces are exerted on different objects, and neither force is zero.
What is one property that a material used to package a fragile object must have in order to protect the object?
Possible answers:
•Soft
•Elastic- meaning the shape can change
Squishy
Durable
•fill the box entirely so there is no room for the object to move around during transit
Sayid has two carts with masses of 200 g and 400 g. He pushes the smaller cart toward the larger cart and they collide. The smaller cart rebounds back in the direction it came from. He measures the force on the smaller cart from the larger cart to be 800N.
What force does the smaller cart exert on the larger cart?
800 N
You can find force by doing mass times acceleration. (F=ma)
Since the acceleration is 4 m/s (see slide 23), and the mass of the smaller cart is 200g, 4 * 200 = 800N.
You can also figure this out because both objects exert and EQUAL force on each other. Since the larger cart exerts 800 N on the smaller cart, the smaller cart also exerts 800 N on the larger cart.
Two bumper cars move toward each other and collide. In what situation would they have the same acceleration during the collision?
The cars would have the same acceleration during the collision if their masses are the same.
A golfer has a choice of several golf clubs with different masses that he can use to hit a golf ball. He can swing all the clubs at the same speed. If he wants to hit the golf ball as far as possible, which club should he use?
A- the club with the greatest mass because it will provide the largest force to the golf ball.
B- the club with the greatest mass because it will have a greater acceleration.
C- the club with the smallest mass because it will provide the largest force to the golf ball.
D. The club with the smallest mass because it will have a greater acceleration.
A- the club with the greatest mass because it will provide the largest force to the golf ball.
Note- Even though the objects would exert an equal, opposite force to each other at the start of the collision, the force applied to the golf ball can be found by the formula F=ma, or Force = mass times acceleration. Since the golf club with the greatest mass will be multiplied by acceleration, it is creating more force than a golf club with less mass would apply.
Sam stands still on a football field, wearing a helmet, while his friend Jaleel throws balls at Sam’s head. Describe the motion of the helmet and the ball before AND after the collision.
Before the collision the helmet is not moving, but the ball is moving toward the helmet.
After the collision, the ball will accelerate in the opposite direction of the helmet. The helmet will accelerate in the opposite direction of the ball, but will not accelerate as fast because it has more mass.
If Sam stands still on a football field, wearing a helmet, and his friend Jaleel throws a ball at Sam’s head, explain how the helmet helps protect Sam’s head.
The helmet will deform, which takes some of the energy from the collision. Sam will not feel the force of the collision as much as he would if he was not wearing the helmet.