A ball accelerate downward at 9.8 m/s2 with 1.7 of force. What is the mass of the ball?

You are driving down the highway late one night at 20 m/s when a deer steps onto the road 35m in front of you. Your reaction tim

8090 [49]

Answer:

- Distance between car and the deer when the car stopped = 20 m

- The time required for you to stop once you press the brakes = less than 5 s in order not to hit the deer.

Explanation:

Using the equations of motion,

In the 0.5 s reaction time, we need to first calculate how far he has travelled in that time.

a = 0 m/s² (Since the car is travelling at constant velocity)

x = ?

Initial velocity = u = 20 m/s

x = ut + at²/2

x = 20×0.5 + 0 = 10 m

From that moment,

a = - 10 m/s²

u = initial velocity at the start of the deceleration = 10 m/s

v = final velocity = 0 m/s

x = ?

v² = u² + 2ax

0² = 10² + 2(-10)(x)

20x = 100

x = 5 m

Total distance travelled from when the deer stepped onto the road = 10 + 5 = 15 m

Distance between car and the deer when the car stopped = 35 - 15 = 20 m

b) To determine the time required to stop once you step on the brakes

u = 10 m/s

t = ?

v = 0 m/s²

x = distance from when the brake was stepped on to the deer = 35 - 10 = 25 m

x = (u + v)t/2

25 = (10 + 0)t/2

10t = 50

t = 5 s

Meaning the time required to stop once you step on the brakes is less than 5s.

6 0

3 years ago

If the spring constant is doubled, what value does the period have for a mass on a spring? A. The period would double by square

antoniya [11.8K]

Answer:

The period would decrease by sqrt(2)

Explanation:

The restoring force is given by,

F = -kx

According to Newton's second law of motion,

ma = -kx

ma + kx = 0

The time period is given by,

T = $\frac{2\pi }{\omega }$

Where $\omega$ is the angular velocity and it is given by,

$\omega$ = $\sqrt{\frac{k}{m} }$

Now if the spring constant is doubled then,

$k_{2} = 2k$

Thus,

$T_{2}$ = $\frac{2\pi }{\sqrt{\frac{2k}{m} } }$

$\frac{T_{2} }{T} = \frac{\frac{2\pi }{\sqrt{\frac{2k}{m} } }}{\frac{2\pi }{\sqrt{\frac{k}{m} } }}$

$\frac{T_{2} }{T} = \sqrt{\frac{k}{2k} } = \sqrt{\frac{1}{2} }$

$T_{2} = \frac{T}{\sqrt{2} }$

Thus, The period would decrease by sqrt(2).

Hence, option D is correct.

3 0

3 years ago

Read 2 more answers

A system of releases 125kJ of heat while 104kJ of work is done in the system. Calcilate the change om imternal energy (in kJ)

artcher [175]

Answer:

DU = 21 KJ

Explanation:

Given the following data;

Quantity of heat = 125 KJ

Work = 104 KJ

To find the change in internal energy;

Mathematically, the change in internal energy of a system is given by the formula;

DU = Q - W

Where;

DU is the change in internal energy.

Q is the quantity of energy.

W is the work done.

Substituting into the formula, we have;

DU = 125 - 104

DU = 21 KJ

4 0

2 years ago

A 2kg mass is moving at 3m/s. What is its kinetic energy?

Illusion [34]

<h2><u>KINETIC ENERGY</u></h2>

<h3>Problem:</h3>

» A 2kg mass is moving at 3m/s. What is its kinetic energy?

<h3>Answer:</h3>

$\color{hotpink} \bold{9 \: J} \\$

— — — — — — — — — —

<h3>Formula:</h3>

To calculate the velocity of a kinetic energy, we can use formula

$\underline{ \boxed{ \tt KE = \frac{1}{2} m{v}^{2} } }$

where,

v is the velocity in m/s
KE is the kinetic energy in J (joules)
m is the mass in kg

— — —

Based on the problem, the givens are:

KE (Kinetic energy) = ? (unknown)
m (mass) = 2 kg
v (velocity) = 3 m/s

<h3>Solution:</h3>

To get the velocity, substitute the givens in the formula above then solve.

$\: \: \tt KE = \frac{1}{2} m{v}^{2} \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \tt \: KE = \frac{1}{2} \times 2 \times {(3)}^{2} \\ \tt \: \: \: \: \: \: \: \: \: \: \: \: \: \: KE = \frac{1}{2} \times(2\times 9) \\ \tt KE = \underline{ \boxed{ \blue{ \tt9 \: J}}}$

Therefore, the kinetic energy is 9 Joules.

3 0

2 years ago

Please help ASAP....

Solnce55 [7]

Explanation:

its easy everone can do it .....let me know

5 0

3 years ago