Answer:
3. 0.5 sec.
Explanation:
A bullet fired horizontally follows a projectile motion, which consists of two independent motions:
- A horizontal motion with constant speed
- A vertical motion with constant acceleration, g = 9.8 m/s^2, towards the ground
The time taken for the bullet to reach the ground can be calculated just by considering the vertical motion:
where y is the vertical position at time t, h is the initial height, and is the initial vertical velocity of the bullet.
Since the bullet is fired horizontally, . So the equation becomes
And the time that the bullet takes to reach the ground can be found by requiring y=0 and solving for t:
As we can see, in this equation there is no dependance on the initial speed of the bullet: therefore, if the bullet is fired still horizontally but with a different speed, it will still take the same time (0.5 s) to reach the ground.
Answer:
1.78 J
Explanation:
Find the spring coefficient using Hooke's law:
F = k Δx
23 N = k (0.20 m − 0.14 m)
k = 383.33 N/m
The work is the change in energy:
W = PE₂ − PE₁
W = ½ kx₂² − ½ kx₁²
W = ½ k (x₂² − x₁²)
W = ½ (383.33 N/m) ((0.17 m)² − (0.14 m)²)
W = 1.78 J
120 just multiply the number then you can find the right answer
Answer:
how close to the true value a measurement is
The Formula we use to work out this question is:
Q=m*c*ΔT
Where,
- Q= Thermal Energy (J)
- m= Mass of object (kg)
- c= Specific heat capacity (J/kg^C)
- ΔT = Change in Temperature. (°C)
Firstly we want to substitute the values in: (Note, ΔT is Negative as we are lowering the temperature)
Q=0.25kg * 2020J/kg^ C * (-7°C)
This gives us:
Q= -3535 J.
This means that 3535J of thermal energy must be removed from the block of ice in order to lower its temperature by 7°C.