Answer:
a) 1.67 m/s
b) 23kJ
Explanation:
We need to apply the linear momentum conservation formula, that states:
in this case:
the initital kinetic energy is:
and the final:
The energy lost is given by:
The table is almost perfect. BUT ... since she called ay negative, that means she's calling the upward direction positive-y and the downward direction negative-y. In that case, since the ball moves downward from the deck to the pavement, the change in y should be negative 3.2 m. Everything else in her table is fine. Choice-D is the good one.
Now, regarding the speed of the ball ...
How long does it take to fall 3.2 m ?
Use the formula. D = 1/2 g T^2 .
3.2 = 4.9 T^2.
T^2 = 3.2/4.9
T = √(3.2/4.9) = 0.808 second.
The ball hit the pavement 0.808 second after it rolled off the deck. So that's also the time it took to move the 0.75 m horizontally.
Speed = distance / time
Speed = 0.75 m / 0.808 second
Speed = 0.928 meter/second .
Answer:
they meet at distance 25 feet
Explanation:
given data
acceleration of car = 8 ft/s²
truck speed = 10 ft/s
car initial speed u = 0
truck acceleration = 0
to find out
How far from the starting point will car overtake the truck
solution
we apply here equation of motion
s = ut + 0.5 ×a×t² .............1
here s is distance and a is acceleration and t is time u is initial speed
so truck distance
s = 10t + 0.5 ×0×t²
s = 10 t ...............2
and car distance
s = 0+ 0.5 ×8×t²
s = 4×t² ..........................3
so from equation 2 and 3
10 t = 4×t²
t = 2.5 s
so both meet at distance
s = 10 (t)
s = 10 ( 2.5 ) = 25 ft
so they meet at distance 25 feet
Answer:
<em>Correct answer: 2) 2p</em>
Explanation:
<u>Momentum</u>
Momentum is a measurement of mass in motion or how much mass is in how much motion. The symbol for momentum is p and is defined as:
p = m . v
Where m is the mass of the object and v is the speed. Note this is the scalar version of the formula because both p and v are vectors.
Suppose the mass of the object is doubled to 2m, then the new momentum is:
p' = (2m) . v = 2 m . v
Or, equivalently:
p' = 2p
Correct answer: 2) 2p
Answer: 22.8 g
Explanation:
1) density = mass / volume ⇒ mass = density × volume
2) density of magnesium = 1.74 g/cm³ (from internet)
3) volume of a block = length × width × depth
volume of the magnesium block = 2.5cm × 3.5 cm × 1.5 cm = 13.125 cm³
4) mass of the magnesium block = 1.74 g/cm³ × 13.125 cm³ = 22.8375 g.
Rounding to 3 significant figures, mass = 22.8 g ← answer