Example 8-15: Power needs of a car. Calculate the power required of a 1400-kg car under the following circumstances: (a) the car climbs a 10° hill (a fairly steep hill) at a steady 80 km/h; and (b) the car accelerates along a level road from 90 to 110 km/h in 6.0 s to pass another car. Assume that the average retarding force on the car is F= 700 N throughout. gsin

Starting from rest at t = 0, a 5.0-kg block is pulled across a horizontal surface by a constant horizontal force having a magnitude of 12 N. If the coefficient of friction between the block and the surface is 0.20, at what rate is the 12-N force doing work at t = 5.0 s? 26 kW 0.12 kW 0.14 kW 12 kW 0.13 kW

A crate of mass 9.8 kg is pulled up a rough incline with an initial speed of 1.54 m/s. The pulling force is 104 N parallel to the incline, which makes an angle of 20.5° with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 4.94 m. (d) What is the change in kinetic energy of the crate?_ J(e) What is the speed of the crate after being pulled 4.94 m?_ m/s

In the figure below, a block of ice slides down a frictionless ramp at angle 0 = 50° while an ice worker pulls on the block (via a rope) with a force Fr that has a magnitude of 45 N and is directed up the ramp. As the block slides through distance d = 0.31 m along the ramp, its kinetic energy increases by 60 J. How much greater would its kinetic energy have been if the rope had not been attached to the block? ---Select--- F. A

A motorist driving a 1332-kg car on level ground accelerates from 20.0 m/s to 30.0 m/s in a time of 5.00 s. Ignoring friction and air resistance, determine the average mechanical power in watts the engine must supply during this time interval.

A skier who initially stands still and weighs 72 kg (including skis) begins to slide down the inclined surface at an angle of 18° to the horizontal. The coefficient of kinetic friction between the skis and the snow surface is μk = 0.12. Calculate the net work done by the forces acting on the skier during the first 7 seconds of the slide.

A box is given a push across a horizontal surface. The box has a mass m, the push gives it an initial speed of V₁, and the coefficient of kinetic friction between the box and the surface is Mk. (a) Use energy considerations to find an expression for the distance the box moves before it stops. (Use any variable or symbol stated above along with the following as necessary: g.) d = 2μ8 (b) What If? If the initial speed of the box is increased by a factor of 4, determine an expression for the new distance dnew the box slides in terms of the old distance d. d

Suppose the ski patrol lowers a rescue sled carrying an injured skiier, with a combined mass of 77.5 kg, down a 60.0° slope at constant speed, as shown in the Figure. The coefficient of kinetic friction between the sled and the snow is 0.100. b)How much work, in joules, is done by the rope on the sled over this distance?

A snowboarder with a mass of 98kg is initially stationary on a hilltop, then slides down on the snowy incline with a kinetic friction coefficient of 0.030 between tl snowboard and the surface. The hill has an approximate angle of elevation equal to 38° from the horizontal and an uphill wind hits him with a force of 0.80N. If the hill is 120m high, what is the speed of the snowboarder as he reaches the ground level? O 48m/s O 34m/s O 42m/s O 30m/s

An object with mass ? = 1.6 kg is released from rest at a height ℎ = 8 m from the top ofan inclined plane. It slides down the inclined plane without friction then slides across arough surface with a coefficient of kinetic friction ?? = 0.4.  What is the speed of the object after it slides 4.2meters across the rough surface?