All categories

3 years ago

13. If both the directions of velocity and acceleration are negative, ...........

Physics

1 answer:

lawyer [7]3 years ago

3 0

Answer:

B)velocity of object decreases

Explanation:

Consider the positive x axis as positive direction

Assume a body moving in negative x-axis direction

It's acceleration also alone negative x-axis direction

So according to our consideration

velocity and acceleration values are negative

That is both are towards negative x direction

But as both velocity and acceleration are in same direction, MAGNITUDE of velocity increases

But as magnitude increases in negative direction, velocity value decreases

But speed value increases(As speed is scalar and velocity is a vector)

You might be interested in

A soccer ball initially at rest rolls down a hill with an acceleration of 3.0 m /s2 .it accelerates for 5 seconds before melissa

slavikrds [6]

The correct answer is the Soccer ball is 3.2 plus 5 that’s your answer.

6 0

3 years ago

It requires a force of 100 N to stretch a spring of negligible mass by a distance of 0.1 m. If the spring instead stretches a di

Mariana [72]

by the formula of spring force we know that

$F = kx$

here we know that

$F = 100 N$

$x = 0.1 m$

now we will have

$100 = k \times 0.1$

$k = 1000 N/m$

now by similar way if the stretch in spring is 0.25 m

force is given by

$F = kx$

$F = 1000 \times 0.25$

$F = 250 N$

so it will require F = 250 N force

5 0

3 years ago

Read 2 more answers

7. A roller coaster’s velocity at the top of a hill is 10 m/s. Two seconds later it reaches the bottom ofthe hill with a velocit

zheka24 [161]

Answer:

7) $a=8m/s^2$

8) $a=-5m/s^2$

9) $a=-1.5m/s^2$

10) $v=29.4m/s$

Explanation:

For the problems 7, 8 and 9 we just apply the definition of acceleration, since no more information is given, which is:

$a=\frac{\Delta v}{\Delta t}=\frac{v_f-v_i}{t_f-t_i}$

So for each problem we will have:

7) $a=\frac{26m/s-10m/s}{2s}=8m/s^2$

8) $a=\frac{10m/s-25m/s}{3s}=-5m/s^2$

9) $a=\frac{0m/s-15m/s}{10s}=-1.5m/s^2$

For the problem 10, we use the equation of velocity in accelerated motion:

$v=v_0+at$

Since the ball starts from rest and the acceleration is that of gravity (we take the downward direction positive), we have:

$v=(0m/s)+(9.8m/s)(3s)=29.4m/s$

5 0

3 years ago

The cost of electricity varies widely throughout the United States; $0.120/kWh is a typical value. At this unit price, calculate

strojnjashka [21]

Answer: a) $1.6123 , b) $0.00588 c) $0.392

Explanation:

Note, all power in watts is converted to kilowatts and all units of time is converted to hours.

The cost of electricity is $0.12 for 1kwh.

Question a.

Power = 40w to kilowatts = 40/1000 = 0.04kw

Time = 2 weeks to hours = 24 * 14 = 336 h.

Energy = power * time.

Energy = 0.04 * 336 = 13.44kwh.

If 1kwh cost $0.12, then 13.44 kwh will cost

0.12 * 13.44 = $1.6132.

Question b

Power = 980w to kilowatts = 980/1000= 0.98kw

Time = 3 minutes to hours = 3/60 = 0.05 h

Energy = power * time

Energy = 0.98 * 0.05

Energy = 0.049kwh

If 1kwh cost $0.12, then 0.049 kwh will cost

0.049 * 0.12 = $0.00588

Question c

Power = 4900w to kilowatts = 4900/1000= 4.9kw.

Time = 40 minutes to hours = 40/ 60 = 0.67.

Energy = power * time

Energy = 4.9 * 0.67

Energy = 3.267 kwh

If 1 kwh cost $0.12, then 3.267kwh will cost

3.268 * 0.12 = $ 0.392

4 0

3 years ago

Trevor and Nick are taxi drivers. Trevor drives a taxi using diesel oil while Nick drives a taxi using LPG. Whose taxi will caus

Natalija [7]

Answer:

Trevor's taxi would cause higher levels of air pollution

Explanation:

Trevor's taxi use diesel oil.

Diesel is less cleaner than LPG.

Compared to automotive pollution from petrol and diesel, pollutants from LPG-driven cars include lower amounts of petroleum hydrocarbons, nitrogen oxides , sulphur oxides, ozone contamination and particulate matter.

8 0

3 years ago