Answer:
Magnets strongly attract materials which already themselves have magnetic domains. They do not significantly attract many metals like gold, aluminum, silver, and even some types of high-chromium stainless-steel, which lack such domains. In fact, pure gold is slightly repelled.
Explanation:
The magnitude of the racquetball's change in momentum is 0.59 kgm/s approximately.
Given that a racquetball with a mass of 42 g is moving with a horizontal speed of 7 m/s to the right (+x direction).
mass m = 42g = 42/1000 = 0.042kg
initial velocity before collision u = 7 m/s
It hits the wall of the court and rebounds to the hitter with a horizontal speed of 7m/s to the left (-x direction). That is,
velocity after collision v = 7 m/s
To calculate the magnitude of the racquetball's change in momentum, we will use the formula below
Change in momentum = Mv - Mu
Since momentum is a vector quantity, we will consider the direction.
Change in momentum = 0.042 x 7 - ( 0.042 x - 7)
Change in momentum = 0.294 + 0.294
Change in momentum = 0.588 kgm/s
Therefore, the magnitude of the racquetball's change in momentum is 0.59 kgm/s approximately.
Learn more on momentum here: brainly.com/question/402617
Answer:
The liquid formed from a melted solid has the same mass as the solid has.
Explanation:
As long as no water can escape, the mass of the ice before melting must equal the mass of the liquid water after.
Answer:
a. If an object's speed is constant, then its acceleration must be zero.
FALSE
As we know that acceleration is defined as the rate of change in velocity

so we can not say anything about the acceleration when speed is given to as and no information is given about velocity
b. If an object's acceleration is zero, then its speed must be constant.
TRUE
As we know that acceleration is defined as the rate of change in velocity

Since we know that if acceleration is 0 then velocity must be constant and hence speed is also constant
c. If an object's velocity is constant, then its speed must be constant.
TRUE
Since velocity is constant then it shows that its magnitude and direction both are constant so its speed is also constant.
d. If an object's acceleration is zero, its velocity must be constant.
TRUE
As we know that acceleration is defined as the rate of change in velocity

Since we know that if acceleration is 0 then velocity must be constant
e. If an object's speed is constant, then its velocity must be constant.
FALSE
Speed is just the magnitude so we can not say about its direction and hence if speed is constant then velocity may or may not change
Answer:
1456 N
Explanation:
Given that
Frequency of the piano, f = 27.5 Hz
Entire length of the string, l = 2 m
Mass of the piano, m = 400 g
Length of the vibrating section of the string, L = 1.9 m
Tension needed, T = ?
The formula for the tension is represented as
T = 4mL²f²/ l, where
T = tension
m = mass
L = length of vibrating part
F = frequency
l = length of the whole part
If we substitute and apply the values we have Fri. The question, we would have
T = (4 * 0.4 * 1.9² * 27.5²) / 2
T = 4368.1 / 2
T = 1456 N
Thus, we could conclude that the tension needed to tune the string properly is 1456 N