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lbvjy [14]
3 years ago
14

Question 3 of 10

Physics
1 answer:
ExtremeBDS [4]3 years ago
3 0

Answer:

b

Explanation:

the law says that energy can not be created or destroy but can be transform from one energy to another.

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28. (a) A daredevil is attempting to jump his motorcycle over a line of buses parked end to end by driving up a 32° ramp at a sp
Ad libitum [116K]

Answer:

a) # buses = 7  

Explanation:

For this exercise we use the kinematic equations, let's find the time it takes to reach the same height

   

     y =v_{oy}  t - ½ g t²

Let's decompose the speed, with trigonometry

      v₀ₓ = v₀ cos θ

      v_{oy} = v₀ sin  θ

      v₀ₓ = 40 cos 32

      v₀ₓ = 33.9 m / s

      v_{oy} = 40 sin32

      v_{oy} = 21.2 m / s

When it arrives it is at the same initial height y = 0

         0 = (v_{oy} - ½ gt) t

That has two solutions

       t = 0                    when it comes out

       t = 2 v_{oy} / g       when it arrives

       t = 2 21.2 /9.8

       t = 4,326 s

We use the horizontal displacement equation

       x = vox t

       x = 33.9   4.326

       x = 146.7 m

To find the number of buses we can use a direct proportions rule

    # buses = 146.7 / 20

    # buses = 7.3

    # buses = 7

The distance of the seven buses is

     L = 20 * 7 = 140 m

b) let's look for the scope for this jump

     R = vo2 sin2T / g

     R = 40 2 without 2 32 /9.8

     R = 146.7 m

As we can see the range and distance needed to pass the seven (7) buses is different there is a margin of error of 6.7 m in favor of the jumper (security)

7 0
3 years ago
If the two forces on an object are equal in size and opposite in direction, the forces are balanced, and no change
murzikaleks [220]

Answer:

a rope being pulled from both sides with equal force

Explanation:

:)

4 0
3 years ago
In a real isothermal expansion, the temperature of the surroundings must be________the temperature of the gas.
Lady_Fox [76]
Must be isolated from the temperature of the gas
7 0
3 years ago
A boy whirls a stone in a horizontal circle of radius 1.8 m and at height 1.8 m above level ground. The string breaks, and the s
umka2103 [35]

Answer:

Acceleration is 148.33\ m/s^{2}

Solution:

As per the question:

Radius of the circle, R = 1.8 m

Height above the ground, h = 1.8 m

Horizontal distance, x = 9.9 m

Now,

The magnitude of the centripetal acceleration can be calculated as:

a_{c} = \frac{v^{2}}{R}        

where

v = velocity

R = radius

a_{c} = centripetal acceleration

Now, if we consider the vertical component of motion only, then considering the initial velocity, 'u' = 0, from kinematic eqn:

h = ut + \frac{1}{2}gt^{2}                

h = 0.t + \frac{1}{2}gt^{2}                

t = \sqrt{\frac{2h}{g}}                

t = \sqrt{\frac{2\times 1.8}{9.8}}

t = 0.606 s

Now, for the horizontal component of velocity:

x = vt

v =\frac{x}{t}

v =\frac{9.9}{0.606} = 16.34\ s

Now, we know that the centripetal acceleration is given by:

a_{c} = \frac{16.34^{2}}{1.8} = 148.33\ m/s^{2}        

                                                                                                                                                                                                                                           

6 0
3 years ago
Marvin lifts a box over his head. The work done on the box is- -Negative work -No work -Positive work
NemiM [27]

Answer:

Positive work

Explanation:

When work and the exerted force are in the same direction, then the work done is positive.

In the question, we understand that Marvin lifts a box up (i.e. over his head). The force to lift the box acts in the upward direction and the work done itself is also in the upward direction (from the floor to Marvin's head).

Since these two are in the same direction, then we can conclude that the work done is positive.

6 0
3 years ago
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