A) A ball sits motionless on the ground
B) A ball gathers speed as it rolls downhill
C) A ball accelerates as it falls out of a classroom window
D) A ball returns to your hand after you throw it up in the air
2 - The space shuttle is located exactly half way between the earth and the moon. Which statement is true regarding the gravitational pull on the shuttle?
A) The moon pulls more on the shuttle
B) The earth pulls more on the shuttle
C) Both are equal due to equal distances
D) Both are equal due to the mass of the shuttle
3 - In which situation is the acceleration of the car negative?
A) The velocity of the car was 75/h over 4 hours
B) The velocity of the car reduced from 50 km/h to 35 km/h over one minute
C) The velocity of a car increased from 40 km/h to 75 km/h over 15 minutes
D) The velocity of a car was 45 km/h at 2:00 pm and at 4:00 pm the velocity of the car was 85 km/h
1. A) A ball sits motionless on the ground
Newton's First Law of inertia states that:
"When the forces acting on an object are balanced, the object stays at rest (if it was at rest) or continues its motion with constant velocity (if it was in motion)"
Among the options given, we see that the option
A) A ball sits motionless on the ground
is an example of this law: in fact, the ball sits at rest on the ground, the forces acting on it are balanced, so the ball stays at rest.
2. B) The earth pulls more on the shuttle
The gravitational attraction exerted by a planet on the shuttle is given by
where
G is the gravitational constant
M is the mass of the planet
m is the mass of the shuttle
r is the distance between the shuttle and the planet
In this problem, we are comparing the gravitational pulls exerted by the Earth and the Moon on the shuttle. The distance, r, is the same (because the shuttle is half-way), the mass of the shuttle m is the same, and G is the same. However, the mass of the Earth is greater than the mass of the Moon, so in the formula M is greater for the Earth: therefore, the Earth pulls more on the shuttle.
3. B) The velocity of the car reduced from 50 km/h to 35 km/h over one minute
The acceleration of the car is defined as the ratio between the change in velocity and the time taken:
where vf is the final velocity, vi is the initial velocity, and is the time taken.
In order to have a negative acceleration, the numerator must be negative: this means that the initial velocity, vi, must be greater than the final velocity, vf, and this situation occurs in option B), since the initial velocity is 50 km/h while the final velocity is 35 km/h.
1-a 2-b 3-b
srry had to write more, i go to this school
B To attract mates
C To orient them selves and find food
D To tell animals of there species where they are
Answer:
The higher the better. Inside the atmosphere since sound cant travel without a atmosphere
Explanation:
Answer:
higher evaluations = faster sound travel
any body
Answer:
The height is 80 meters.
Explanation:
The equation for the distance in the second segment of the fall is as below. In it, we use the initial velocity v1 that the ball had after completing the first segment. From this equation, v1 can be determined:
Next, we use the kinematic equation for velocity at the end of the first segment of a free fall, to determine h1:
The total height is then
Answer:
B. Mercury-Venus-Earth-Mars
Explanation: